Gen IV BBC bolt in compatibility with GMT400 platform?

[Metalgear454]

Hi all, new to the forum and apologize ahead of time if I posted in wrong area.

I have a few questions about Big Block Chevy Generation Interchangeability specifically regarding bolting into the GMT400 platform.

Let me paint a picture of my plan first.

I’m a long time motor head, have built a dozen early gen Big Blocks and Small Blocks.
I have finally retired, and I have waited until I'm in my sixties to finally build another Gen IV Big Block, mainly because I've had the parts for the last 35 years (all brand new except a standard bore 4 Bolt 454). (Just need rings, bearings and a Gasket set)

I live in the Northeast and my search for an early Muscle Car has been futile…. Anything I can afford is a nightmare, specifically in the rust department…
My drag racing days are long gone and I just want to build a Stout Street Machine and have always liked the 90’s OBS look.
I can get my hands on a low mileage, garaged 1995 reg cab, 4.3L V-6 c1500 that has no rust.

So, here are my specific questions:

1. What years of the GMT400 platform was a BBC offered and what Gen were they?

2. Is it safe to assume a Gen IV BBC will bolt in on any 88-98 chassis with the proper factory motor mount frame perches (say from the early 90’s – 454SS truck, I’m assuming the bolt locations specifically the motor mounts and Bell housing location and pattern is the same between BBC generations – please correct me if I’m wrong)

3. Do the frame perches even have to be changed from the V6 version?

4. Are headers readily available for this combo?

I know I will be faced with a myriad of computer and transmission issues, but my plan is to run a good old Holley carb and some kind of overdrive trans. Where I live this vehicle will be exempt from emissions testing as it would be over 25 years old. I’m mainly concerned about the Gen IV fitting and bolting into any GMT400 platform…

Any help or thoughts would be appreciated before I commit to purchasing the vehicle.

Thanks!

 

[454cid]

The GMT-400 got the big block every/all years. They started out with the Mk4 and ended with the Gen6 (actually Gen7 if you count the 3500HD cab&chassis).

I've never swapped one, so I don't know about mounts, or what else might need to be changed, but it should all be done pretty easily, assuming no problems with the wallet

 

[Supercharged111]

The rubber mounts bolt to the frame, those are all the same. The only thing that 454 would need are the bits that bolt to the block itself. Then it drops right in. Worst case you drill the frame to move the cross member depending on your trans of choice. But there really is no headache awaiting you as it pertains to bolting in a 454.

 

[Komet]

The 454 is heavier than the v6, you might need a different spring rate in the front to balance things out. If this truck really is a sweetheart deal for a nice chassis, the swap should be fairly bolt-in but you could dig into the fun stuff a lot faster if you started with a 454 truck. As a bonus, you won't have to track down all the specific boring bits you never wanted to know about to do the swap.

 

[Metalgear454]

Thanks guys, I really appreciate the responses, I just didn't want to find out that at a certain year the frame was updated, but I assume the frame is the same for the whole GMT400 generation. Would love to hear from anyone who has attempted a BBC is to where a V6 was! Thanks!

 

[L31MaxExpress]

Thanks guys, I really appreciate the responses, I just didn't want to find out that at a certain year the frame was updated, but I assume the frame is the same for the whole GMT400 generation. Would love to hear from anyone who has attempted a BBC is to where a V6 was! Thanks!

I put a big block in place of a 200 V6, required new frame stands and a lot of other small modifications and some bigger ones like the whole driveline from the Metric 200 to the 7.5" 10 bolt hit the garbage. The 200 V6 is the 4.3L engines older brother based off the 267 V8.

 

[Schurkey]

You're starting a project where a tremendous amount of the original driveline will be entirely unsuitable.

You're going to scrap everything from the radiator to the rear axle, plus the front springs. And that doesn't include repairs due to wear or negligence, like ball joints, idler arm, control arm bushings, rag joint, and so forth.

Re-think this project on a GMT400 that already has a big-block in it.

 

[Metalgear454]

I understand and it's great advice! I'll start looking, it'll be like trying to find that unicorn, but I've got time, I'd rather deal with all the mechanicals rather than a rust bucket project. By me in NY everything this old is big money or is a rust bucket or better yet incorrectly repaired rust all covered up. Give me a clean slate at a decent price and I'll spend whatever on component selection. I'm a ex auto mechanic and then a FAA A&P mechanic, for me there is nothing better than turning wrenches on my own projects, just never did any kind of bodywork. Thank you though, all advice is welcome!

 

[Supercharged111]

Based on the picture OP painted I didn't get the impression he was gonna just drop an engine in and go. This is a project truck. So it should get a 6 lug C2500 swap, hydroboost, 1 ton radiator/shroud, front end rebuild, etc to be a proper cruiser with brakes that stop.

 

[RichLo]

Also note that 1500 trucks have a thinner frame than 8-lug trucks. Not a huge deal for a daily driver but you'll have to stick to the door panels tow ratings even with full 1-ton drivetrain.