1993 Chevrolet C3500 Crew Cab Restoration/Cummins Build

So for those of you who haven't heard, I'm starting a new project on a truck I've wanted to restore for years, a 93 C3500 crew cab that's been in my family for close to 20 years... I got this truck about 2 years ago, daily drove it for just over a year until transmission issues forced me to park it. Since then I've constantly debated what to do with this truck, knowing I want to keep it long term, whereas my other crew cab is just my daily driver for the time being.

Here are a couple pictures of how its transformed since I've owned it. The truck had a all black front end which replaced the factory chrome end years before I had it. I threw some LED signals, tow mirrors, and my extra set of wheels on it, got the front end aligned and drove it. Later I replaced the rusty front bumper with an extra chrome bumper and a junkyard chrome grill. I sold the XD wheels, and threw some PY0's on.







Since the 350 wasn't really cutting it in my red 94 crew cab, I pulled the running 6.5 from this truck, and dropped in the other truck. Knowing I had intentions to keep this truck long term, I spent quite a few months debating what I wanted to do with it. I like the 6.5, however eventually decided to use this opportunity to upgrade the engine to a longer lasting, more durable power plant. I could build a brand new 6.5 for this truck, but the costs push upwards of $3-4k. So I decided to go a different route, by picking up this good running p-pump 12 valve Cummins out of a 95 Dodge.



Now I'm not 100% certain on everything yet, however I'm likely going to stick with the GM 4L80E transmission. I wont be sled pulling, drag racing, or towing 20k with this truck, so I'm confident the 4L80E will hold up.

I will probably elect to run a later style 4L80E with an aftermarket controller. Although the truck could run off the factory TCM, (being a factory DB2 truck) I feel the later style trans with the upgraded internal wiring harness is far less problematic, and the aftermarket controller will allow for tunability with the lower revving 12 valve.



Now although it will be powered by a Cummins Engine, I want to keep this truck as close to factory as possible. The truck will be repainted in its factory white paint, the factory burgundy cloth interior which is in great shape will not change at all. The factory suspension will be serviced, however not modified.

I plan on running no side moldings, but do plan on keeping the factory era 3500 and Silverado badges. Also plan on running he factory amber cab marker and corner lenses with clear headlights for a factoryish look. Will probably use the chrome smoothie bumper and 94+ grille from my other truck. I also want to find one of the remanufactured "Chevrolet" tailgate badges, which is something this truck came with from the factory.



Despite wanting to keep a factory look, I am considering a dually conversion. I've always loved the look of the dually trucks and have always wanted one. With the 12 valve under the hood, it just works.. If I do go this route, this will be the wheel combination I go with. 16" aluminum Alcoa's with factory GM center caps.....

Now I need a new bed regardless, so if I elect against the dually route, and keep it a SRW truck, i'll likely just run an aftermarket 16x8, or 16x10 wheel similar to pro comp soft 8's with factory center caps.


Overall, this will definitely be a slow build as I plan to completely restore the truck in every manner. Here are the plans aside from the possibility of a dually conversion.

Plans for Engine:
95 P-Pump 12 Valve
- ARP Head Studs
- 4K Governor Springs
- Valve Springs
- HE351 Turbo
- Fass or Air Dog Lift Pump
- First Gen Motor Mounts (Will try them before purchasing conversion mounts)
- Factory Dodge Radiator/Intercooler
- Possibly new injectors down the road
- Rebuilt 4l80e Trans, may upgrade to newer style plug as previously mentioned.

Plans for Body/Chassis (aside from possible dually conversion)
- Repair all rust
- LED Turn Signals/Tail Lights
- Keep all amber lenses to resemble factory appearance.
- Stainless steel brake lines
- New Fuel Lines
- New gas tank/fuel sender. (stole the factory tank when swapping my red truck)
- Complete undercoating
- Spray in bed liner
- New Paint Job (factory GM Olympic White)


I'll try to keep this updated, like I said It will not be a quick build by any stretch. I have a good deal lined up on the paint job, so i want to get that done while i can get a good deal on it. The first step will be to get the rust repaired, and the frame undercoated, so I can have the cab painted. Then I'll move forward from there.

Sub'd for build. Really love the truck's history and can't wait to see how it all comes together.

Love this build man. Can't wait to see the end result

So the first update...

decided to go with a 2" body lift. I've talked to many people who've done the swap and have come to the conclusion that its just going to be easier with the body lift. I'm not a huge fan of body lifts, but I think being a 2" lift, I'll be able to hide it. Its really going to pay dividends when it comes to downpipe clearance, I might be able to run a true 4" turbo back exhaust.

Most motor mount sellers say you need to at least modify the firewall to clear the engine. I'd rather not #sledgehammermod the truck. Also, my 18's were stuffed, so the 2" of lift should compensate for that. (Even if the 12 valve sags the front an extra inch)

I also acquired a set of first gen cummins mounts, which supposedly work for these swaps. They were free so we'll see what happens. Worst case scenario I use auto world mounts if I can't get these to work.



Got the front fenders off. Left the core support so I can check radiator clearance.

Even though I haven't resealed the motor or rebuilt the transmission, I'm going to get the adaptor plate and my goal is to have the motor and trans bolted into the truck by Christmas. That way I can work on making sure everything fits and functions before I rip it all back out and paint and undercoat everything.

Also, ran across a rust free dually bed for $300. Of course me being me, then changed my mind and decided against the whole dually idea.

Mostly because I don't tow regularly enough, or heavy enough loads to justify 6 tires. A SRW truck with helper springs will tow a vehicle on a trailer, or a skidsteer with no problem.


Also, i have an idea to possibly do a color change. Was planning on keeping it white, but since the inner sides of my doors have a little surface rust, it's probably just going to be easier to refinish and paint everything.

Alrighty, so i don't have my bellhousing adaptor yet, but i did get my first gen motor mounts, so i decided to do a little test fit. Now i don't have isolators yet, but it still gives me an idea how its all going to fit. Once i get my bellhousing adaptor i can hook up the transmission, and proceed from there.

Now the engine will be coming back out before the swap is complete, but it at least gives me the ability to mock everything up before i clean and paint everything. A lot of guys simply drop the engine in, hook everything up and drive it, but I'm going to practically redo everything, so just a test fit for now.



Another reason i wanted to get the engine into the truck was to mark and examine all of my wiring. This GM technician wiring guide that i bought a few months back should help me with the swap. I'm going to try and run the grid heater somewhat linked in with the glow plug circuit so the factory glow plug light works. Since its a conversion, i wanted to make sure i marked everything. I'm not going to cut ANY of the factory harness. I feel you're asking for trouble when you start doing that. Any unused wires will get tucked into the grommets and fastened and secured away. i'll make sure everything looks visually appealing under the engine bay.

Goal is to make this thing look like it could've been a factory option.



One good thing about this swap, my truck is a 1993 with a 6.5 diesel from the factory, which is a mechanically injected motor just like the Cummins. Everything can continue to work as it did from the factory. As you can see in the picture, the factory cruise cable is the perfect length to work with the dodge throttle linkage bracket, so i shouldn't have to do much to retain my cruise control.



Additionally, all of the gauge senders can be installed on the dodge engine to assure the factory gauges work as they did before the swap.. Heck, i could even have the factory TCM shift the transmission by wiring up the factory TPS to the dodge TPS sensor.

(I do plan on running an aftermarket controller so i can make adjustments, a lot of guys claim they have issues dialing in the TPS with the factory TCM)



Now someone told me the truck would sit higher the heavier Cummins engine than it did with the 6.5... i laughed at him. Somehow, he was right. This thing squats the front end less than the 6.5 did.. Glad he's right because i should be able to run these wheels/tires with a SRW bed. Tossed away the dually idea as i simply don't tow often or heavy enough to justify the extra 2 tires. Now i know i haven't added the radiator, intercooler, bumpers and fluids, but even with me (180lbs) standing on it, it still sits an inch higher than it sat before.

Overall i'm glad i got the engine in, kind of tricky to get the long straight six back in there, but its doable without taking out the core support.. Still have a lot of work to do, even for mock up. At least i got the motor in and the first gen mounts work like they should. I needed to see that. Next step is to order the bellhousing adaptor, install the transmission, install the motor mount isolators and getting the motor bolted in where it needs to go so i can begin working on mocking up other things such as the intercooler, throttle linkage, hoses, piping, exhaust, extend factory wiring as needed, etc.

TIPS:

I've got a request to be rather detailed in this swap, since there isn't a lot of good complete threads on these swaps. I'll try to include the everything i learn along the way for those considering attempting this swap.

First advice i can give, is to talk to as many people as you can. Reach out to guys who have done it, most are willing to share details and advice. From what I've learned thus far, a lot of this swap is about decisions and sacrifices.

Auto World sells great products however can be pricy, destroked sells a good adaptor plate. And lots of other places sell conversion parts as well. I will say, Auto World will bend over backwards to help you, even if you don't buy anything. They have step by step instructions. So, if you're worried about venturing off the beaten path, you can call Auto World, grab their instructions, use their products, and you can follow their guid from start to finish to complete the swap. Its expensive, however worth it to some folks. I'm making decisions as I go based on the parts I have, and cost.

Things to know before you start:

- This is not a cheap swap, even with a donor truck.
- Driveshafts WILL need to be shortened, the motor has to go as far back as possible to provide aqequate clearance.
(front may need lengthened, not sure mine isn't 4x4)
- Front diff bolts will need to be countersunk to allow clearance. Its tight with 4x4s. (you can find pictures online)
- Don't expect to finish this swap in a weekend, its definitely a project.


Decisions to make:

Transmission Selection: (most popular, 4L80E, NV4500, 47RH)

Keep in mind, you'll probably want to find a way to make your factory speedo work. Also if your vehicle is 4x4, make sure you pay attention to mating up your transfer case. if 4x4, VSS will be in the transfer case. Again driveshafts will need modified ether way.

(Keep in mind 4L80E bellhousing adaptor and flywheel run $1000-1300)

Intercooler Selection: (you can run an non intercooled motor, i wouldn't)

Dodge 2nd gen Intercooler: will have to likely trim the parking lights if you want to keep the mechanical fan.

Universal Intercooler: Must make sure that intercooler is sufficent enough to keep the engine cool.

7.3 Powerstroke Intercooler: will have to run a much smaller radiator, again must make sure its sufficient enough to cool the motor, especially if you're doing upgrades to the motor.

Mechanical/Electric Fan:

Electrical/Mechanical. I've talked to guys on both ends of the spectrum. Lots of guys run electric for clearance reasons. However the guys who have mechanical typically have a strong objection to electric fans. I like the reliability of the mechanical fan. Also it is documented that electric fans are not sufficient for towing. I haven't officially decided yet mainly because i don't know how the clearance is going to work, although i'm leaning towards a mechanical fan.

Motor Mounts:

Lots of places sell motor mounts. First gen dodge mounts work if you can find them. Auto world sells a good quality mount with a polyurethane isolator. A lot of other guys make them as well, from complete motor mounts, to kits you weld together yourself. Stay away from the GM style mount with a push through bolt that runs through the factory rubber mount. I've heard of guys running those GM style mounts having serious vibration issues. You can attempt to make your own, however make sure they're durable. Cummins produces a lot of torque.

Body Lift:

Most people say body lifts are not required, and in general i don't think they are necessary.. However, if you don't do a body lift, you will very likely have to modify the firewall, and its all very tight. Most guys create clearance with a hammer around the trans tunnel. I ordered a 2" body lift solely to make my life easier, this should also allow me to a run a larger down pipe.

Alternator/Air Conditioning:

You'll have to find out if you want to run the GM or Dodge alternator (Dodge requires work as its externally regulated, GM are internally regulated) Same with the AC, if you want to keep it. A lot of places sell adapter brackets to run your factory GM components. Another thing you can try to make on your own. worth noting, these adapter components can get very pricey... I'm still undecided on how I plan to run belt driven accessories at this point.


Summary:

Most of these decisions have come with sacrifices, for example. Run the factory dodge radiator and intercooler with a mechanical fan? You're likely never going to have issues with overheating, no matter what you do to the motor. They come with overkill cooling systems from the factory. However you'll have to deal with a tight fit, and trimming your parking lights.

So i'm kind of at a standstill waiting on funding on parts at the moment, so i took advantage of this downtime to extend some of the factory wiring, and re-wrapped all of the loom that was damaged or cracking. All of the GM sensors will be reused with the new motor, however many of these are in new locations. Mainly the alternator which moves from the drivers to passengers side.

I ended up ordering alternator/AC mounts from Syndicate Chop Shop out of Robins Iowa. They take a while to process orders, but everything is made by the owner, and he doesn't outsource anything. This unit mounts in the factory dodge alternator location and stacks the factory Dodge AC unit above the GM alternator keeping both units on the passenger side while retaining the factory belt tensioner. (With this swap you have to relocate the AC regardless as it would hit the frame) The Auto-World (Located in Great Falls Montana) mounts were priced $650 and kept the GM alternator on the drivers side and the factory GM AC on the passenger side. However, their setup runs a 2 belt system requiring you relocate some other components including the oil fill tube, and throttle brackets. I liked syndicates style of the single factory dodge belt, with all of the pulleys on the passenger side.

Only downfall of Syndicate's mounts is the fact that i have to run the dodge AC as they have not yet designed a unit to run the GM AC. That said, I have never had good luck with the old round Delphi style AC compressors, so i'm okay with this change. It was important for me regardless of who i went with to re-use my GM alternator since it runs the factory tach. Only thing i'll have to do is swap out the pulley to match the Dodge belt. The Syndicate setup is still a little pricy, at $250 for the bracketry, and $175 for the dodge AC adapter lines. However, given the price and work involved, it makes it worth the hassel of not having to fab up my own mounts and re-engineer a piece that someone else took the time to engineer and test these types of things. (keep in mind, 1/8th of an inch can cause serious issues with belts)



(Just an FYI, everything will be coming back out after mock up for paint. Truck will be sent off to paint, frame/firewall will be painted as well as the engine.)

So far in this conversion, i have not, and will not cut any of the factory harness. As I mentioned before, doesn't mean I cant clean up the engine bay.

As far as wiring i have a few additions that will join the factory harness.

1. Standalone Grid Heater Harness: Will loop this in with the factory "glow plug" light. That way it will function just like the factory dodge, with the GM wait to start light, so that any idiot can drive it.

2. Electronic Fuel Pressure, Boost, and EGT Gauges: To monitor some things on the old rattle box.

3. Transmission Controller Harness: Being a 93 i could simply re-wire the TPS and have the factory TCM control the shifting. However, i have read lots of guys have had issues dialing them in, so i'll just go ahead and bypass this with a standalone transmission controller. I was very happy with my US Shift Quick 1 controller on my 94 mechanically injected 6.5. That said, Auto World Diesel Conversions had great things to say about the PCS products. Most of the guys i've talked to who kept the 4L80E with the 12valve used PCS as well with good feedback on it.

The guys at US Shift are very helpful, and recently came out with an upgraded controller in the US Shift Quick 4. None of the harnesses changed, but the controller has many new features. As always their unit has a digital screen with fault codes, and constantly is monitoring things such as low line pressure and overheating. Additionally this new Quick 4 unit can detect early transmission slippage. I still haven't decided 100%, but PCS will have to really impress me with their units features for me to turn away from US shift.
Speaking of tranmissions.... As I mentioned above, lot of guys don't use the 4L80E feeling it's not tough enough for the 12 valve. Since the Cummins does put out quite a bit more power than any GMT400 engine, I spoke with the guys at Jakes Performance (4L80E Guru's located in Sanger Texas), and they confirmed that all 4L80E's while slightly different are all reasonably close in terms of durability. I considered upgrading to a later model trans but they advised it wouldn't be necessary. I talked to them about my intentions of a mild cummins build with the 4L80E behind it. They had no concerns about it holding up, in fact recommended their stage 2 kit. They also indicated they thought billet components including a billet converter would be overkill as long as i'm not going too crazy with the motor.


As i said earlier, still waiting on parts... Not going to be a quick build, but i'm learning to live with that. Should be worth it when i'm done.

Okay, so i was feeling ambitious so i decided to tackle one of the biggest obstacles of this swap. Adding the intercooler.

When using the dodge intercooler and mechanical fans, you're going to have clearance issues with your parking lights. Simply inevitable. Most guys have to cut the parking lights completely out on the inner side. However, with my LED's that's not really possible. So i figured i would remove the AC condensor and recess the intercooler as far back as possible right up against the radiator. Even if it required the use of a aftermarket AC condensor.


As you can see, its a lot of intercooler to work with.

Carefully cut out the core support to make it fit, Didn't want to cut or modify the top of the core support or the hood latch, just seems like something that would lead to a headache later on. I'd rather use a universal AC condensor and keep the hood latch mounted how it is. Plenty of room in front of the intercooler for the AC condensor. Going to try and use a 11"x21" universal AC condensor. I could probably use the factory condensor with a diesel bumper and slide the condensor down into the bumper if i absolutely had too.

Aside from the condensor, all thats left will be to mount a heavy duty transmission cooler which i will likely elect to use with a dodge radiator rather than the GM radiator with the cooler built in. Allows me to run a bigger trans cooler and factory dodge radiator hoses.

Once the intercooler was mounted, I was able to get the hood latch bracket bolted in the factory holes. If clearance becomes an issue i will cut out the lower portion of the bracket and fab up mounting brackets for the AC condensor and transmission cooler. I plan on using some sort of rubber piece to cushion the gap between the intercooler and radiator, that way nothing rattles around. Also plan on doing the same for the AC condensor depending on how it all mounts up.

Despite recessing the intercooler far into the core support, i still had to slightly modify the parking lights. I since have resealed the back sides with an insulated foam that should prevent them from heat and water damage.

Clearance is much better than other swaps i've seen.

And it's all back together aside from the fogged headlights which will be replaced. Likely with OE headlights with LED Bulbs.

At least now that the intercooler is in, i can get the radiator in, and slide the motor a little bit further forward. This should give me more trans tunnel clearance while allowing me to keep the mechanical fan. Hoping i can do without that body lift.


Now, I'm not going to go into all of the alternatives, but there are MANY other ways to add an intercooler.... I went with the dodge setup solely because it's a borderline overkill cooling system from the factory, and I didn't want to be limited by the cooling system. I've read many places that towing with electric fans for example is a big no no. The 7.3 Powerstroke intercooler will require you run a custom radiator which is even smaller than the factory 6.5 radiator. Obviously the cooler you can keep these things the better, just wasn't worth the trade off. I've read the universal intercoolers are more efficient, however you'll have to make all custom piping. Since i already have the dodge stuff, i figured it would be easier, and more economical to just use it. Plus, now i can use factory dodge intercooler piping and boots.

This swap is all about decisions, and i'm just trying to make it as easy as possible while using parts that i can get from any local parts store. That way, if i'm in another state and need a intercooler boot, or a radiator hose.... a simple trip to advance auto parts and i'm back on the road.

Here is kind of what i have in mind for the project... a little photoshop. Not a very good one, but you get the idea.



Plan is for a Chrome Smoothie Bumper, factory corners and gold bowtie however with a billet insert, debadged with the factory 3500 emblem on the door with a cummins C above that. Traction bars to put power to the pavement, 4" exhaust with a big 6" 18" long rolled tip out the back corner, a reproduction "Chevrolet" banner across the tailgate and a colormatched roll pan to tie up the back end. Wheels/Tires will obviously be my 18x10's which i seem to run on everything.