frame to frame

[hipasschev94]

how close would the frame of a long box 4x4 73 to 87 full size chevy truck be to an 88 long box 4x4? i want to have a straight axle on my 88 but mostly everything to do it with the existing frame is to expensive plus my frame is junk, but i also want to run dual tanks on it cause im trying to build it vintage so im thinking of just swapping my body and motor over then just use the rest of the drive train thats there

[project 67 sub]

the frames are completey different, that being said the swap can still be done, it just wont be as easy cause it wont be a direct bolt in swap
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[hipasschev94]

i was assuming theyd be diffrent, what would i have to do to get the mounts to line up right?

[hipasschev94]

that wasnt being a smart ass sorry i just read it and it really sounds like it

[project 67 sub]

its ok lol, didnt take it as you being a smart a$$ im not sure exactly what it would take to make it work. maybe move/change frame mounts, maybe make new ones idk, sorry i cant help more, i do know that at least the front half of the 88 frame is alot stronger than the earlier. the 73-87 frames are prone to craking and braking where the steering gear bolts up

[hipasschev94]

What i was thinking was that while I'm working on the new frame that is box it and cap it in key points to make it as strong as it could possibly be but still have some of the flex it needs. Would you happen to know of anyone in Minnesota that has a long box standard cab 4x4 frame with dual tanks and 1/2 axles for sale or trade for a reasonable price?
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[ChevLoRay]

What's the basis for such a swap? You must have a really good reason for asking the question. I know that with enough time and money, virutally anything is possible. My question is why? Help me understand.

[hipasschev94]

Well i have a 88 chevy but I'm building it as vintage as possible and i also prefer straight axle over ifs so to do the swap to the existing frame is about 800 for the swap kit then another 400 for the crossover steering then buy the axles seprate for another couple 100 then i could just buy the older frame be able to buy everything cheaper and get everything at once like frame axles dual tanks ect. I can't afford all that much so I'd rather do the work and have everything work better
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[ChevLoRay]

Okay. I was just curious. Good luck.

[bloertcher]

Here's the skinny on the task your proposing.I did it close to ten years ago on a truck that I built for mudracing.
The 73-87 frame is right around 12" narrower than the later frame.I had to incorporate roughly 4" of body lift to get the body to set level and look "correct".
EVERY body mount,and even bed mounting point took a lot of fabricating,and being a race truck I didn't use body bushings.Nor did I have bumpers,which would open a whole nother' can of fabricating worms.
The dual tank thing,I've had a few dual tank square body Chevys,they ALL had issues.If the tank switch worked when I got the truck,it always had at least one issue before it was over.GM didn't do away with dual tanks and incorperate a large single tank because the dual tanks were so successful.Theres a lot of extra parts involved in dual tanks,and even the best parts fail.

Honestly,it is a doable swap,but it really isn't worth it.I had to brace the hell out of the frame,and build extra crossmembers,due to the "twisting" force that having such long "body mounts" on the frame gave.I wholeheartedly understand the swap kit being expensive.It shouldn't cost what it does,but they HAVE engineered it,and it is SAFE.
This is my advice,and worth just what it costs you,but if I were in your shoes,I would study anything I could find on straight axle swaps,caster and pinion angles,and steering solutions.If you can't swing the ORU kit,build it.I promise the results will be better and SAFER than swapping to the earlier frame.

[ChevLoRay]

Voice of Experience....