body swap thread. gmt400 on gmt800 chassis

[Van Gui1d3r #838]

I have a bare 800 extended cab frame in my shop right now, I will go take a few rough measurements against my 400 extended cab frame. Just a word of caution, IMHO the 800 frames are more rust prone then the 400 frames. I will get back to you later today.

ok thankyou. i already checked the wheelbase, 800s are and inch and a half to 2 inches longer so like i said i would put the cab on correct, then box, then cut the box sides out so i can swap them side for side and have them locate over tire correctly... box wheel well should be 3/4 to and inch farther back. dont think anyone will pick up on that

 

[RyanMerrick]

Cool idea. Take a lot of photos and post your progress if you decide to do it, a lot of people would be interested in seeing it

 

[NacIK]

I wouldn't personally do it myself, but I would love to see it. Just like the marine manifold conversion and 411 swaps that were done a few years back. Good luck with it.


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[Van Gui1d3r #838]

my entire purpose to go through with it will be because i have all the body pannels i need to fix my truck and i absolutely love her. but these gmt400 chassis are nowhere near as rugged as a gmt800 and the powerplants are nothing compared to the lsx 3rd gen motors. if i can id like to find a 2500hd extended cab short bed, 8 lug axles and 6.0 powerplant would be sick

 

[phule]

If all your gaining is the motor and trans why do it? Is there any gains with the frame itself?

Adam

 

[Van Gui1d3r #838]

If all your gaining is the motor and trans why do it? Is there any gains with the frame itself?

Adam

main gain is its a better chance at finding a newer frame up north in good condition than an older one, after that, the gmt800 chassis is way more rugged and the brakes are 4 wheel disc... to convert a gmt400 over to everything the 800s have would probably cost more not gonna lie and then youd have to deal with the frame not being as rugged...

 

[Hezsus]

I think you would be better off getting a gmt 800 hd with one of those silly motors that dosent have spark plugs and puts out 6-700 ft lbs. put you gmt 400 body on that. get a proper retrofit harness made (trust me its worth it).

Some things to keep in mind though:
The front rad supports will need some serious fab work
For the box, Just buy side panels and you can cut the wheel openings where needed.
Gas Tank Position.
Shift Linkage
Steering Adapter
Firewall Clearance

The actual mounting of the body to the frame is the easy part.

I'm very interested in this though

ps. put a 6.6 in it

 

[94_C/1500]

As rusty as things get around here, I'm sure I can find a complete, driving 4x4 GMt400 for $1000 and a 2wd for $500. The body's may be rusty, but I'm sure I could one with a good frame. Even if you have to drive a few hours to find a good deal, it'd so much easier than putting a 400 body onto an 800 chassis. I've seen both 400s and 800s very abused with no frame damage. I know of a C1500 with doubled up springs in the back haul 2 1/2 tons of shingles in the bed. It did the speed limit to dump too, about an hour drive. It did it several times. This truck had also hauled several stupid loads, never broke. Ended up getting totaled by someone running a red light. I've seen another C1500 (same owner) yank logs out by the front bumper, messed the bumper up but the frame wasnt hurt. So I'd love to see a broken 400 series frame that wasnt caused by rust. I suggest you find another 400, use its frame under your truck.

 

[gd1]

if you have to ask "how hard is it to _______" then you probably can't do it...

 

[benjaminbarton55]

I swapped the body on my gmt400 over onto another gmt400 frame. If I could undo all I did I would. All it did was make things worse. Amd the hours involved is rediculous. And your talking about a whole different frame here. Unless you have something else to drive amd tons of spare time, and this is just a custom restore like project.. I wouldn't even do it. I had a local shop help me. And that alone took a month. If you plan on doing this just be careful! Giving you props for an interesting idea though! You being a machnist might make it easier to modify. Just some of us dont have all that hefty knowledge!

Hope all goes well!



Goodluck buddy