Frame swap

[charlieo]

First time I've been here . I'm asking for my father-in-law . Has anyone here put a 69 GMC frame (Coil rear) under a 55 series 2 body ? And what is involved ? Both are 2wheel dr. Thanx.

[DennyB]

If there both shortbed models you will need to weld in new cab, rad. support and bed mounts. Also will need a new steering shafts and alter brake lines.
Why not use a 71-72 chassis and get disc breaks?

Hope this helps.

[charlieo]

Both are long beds and I thought it wouldn't be to hard to find disc brakes for the front after we got the frame under it ! Do you know what rear end diff the second series 55 had under it ? Is it a Eaton rear and are there any ring & pinions still avail for them ?

[dubie]

I may end up doing the same swap on the wifes 58. I need to cut the frame down first to the 115" wheel base for a shorty and then fab up the supports. I happen to have a nice straight 72 lwb rolling chassis sittin around doing nothing. I also have a 70 lwb rolling chassis that I need to do something with.

[DennyB]

I'm not sure on the lwb dimensions of 55-2nd/69.
There were alot of rears installed in these trucks and it depends on whether its a 1/2 or 3/4 ton as well.
Post a pic of the rear and that will help.
Danas, GM 12 bolts and Gm corporate/Eaton rears were used in these trucks.
Lots of gears aval for all but the eatons. Gears are aval for the eatons but the ratios are limited.

[charlieo]

I'm pretty sure it's a Eaton but I think if he can find the time/money/place to do the swap he'll just use my old 9 frame ! Thanx for the help !!!

[DennyB]

Your welcome although I'm not sure I was much help.

btw, what is a "9 frame"?

If your refering to a 90s chassis pay attention to the wheel width for fitment

Tim,
Whats the outside width of the front wheel on that 72?

I measured my 56 and got this on the body..

The box is 4'-3" wide with about 12" on each side to tuck tires in.
In the front which is probably more critical, I have 70" in width from the inside fender lip.

I'm having a devil of a time finding a modern 4wd chassis to fit width wise.
I hate to use an S10 because they eat front-ends with the light S10 body. I'll have to check on the 4x4s. Wonder if their IFS????
An extended cab 4x4 should work but then I'm dealing with weak rears.

If something dont start looking up soon Im gona start looking at ford and toyota chassis!

[charlieo]

I meant to type 69 frame & I posted it without noticing it in time . LOL !

[dubie]

I just measured the width from the outside of the tires on the 72 frame and it was 71". Then I went to the 58 and it measured 69" in width. So it looks like it should work out perfect. The 58 has that Nova front clip and a Nova rear end in it, so it's a bit narrower to start with.

[DennyB]

Thanks Tim!!!
Is that to stock width tires?

[dubie]

the tires are 205 75 R 15's on the 72 frame so damn near stock. It looks to me that it is a great swap for the 55-59 era

[DennyB]

Tim,
I agree!! Best match so far (see my new sig)
Any extra I think I can make up with the wheel back space.
I think I'll start a new post on the 4x4 board for my additional questions
charlieo,
Hey man, I'm sorry for high jacking your thread.
Perhaps you got a little out of it too.

[Bob Chayer]

Hello from NH,

I thinking of the same project but I was going for 4wd. We need it up here in the snow belt! Any idea how wide the truck body is? I need to know if the body will be wide enough in the front to cover the width of the axles. Also I pulled out the tape and found a '71 1/2 axle with 235/75/15 tires and 7" white spoked wheels is 76" from outside of tire to outside of tire. A '72 3/4 ton axle with 265/75/16 tires and stock 7" steel wheels is 78". I think the 3/4 axle is 2" wider than the 1/2 ton by design. I believe a couple inches could be "chopped" of these lengths with different wheels and tires. Not sure if this info helps but I thought I would pass it along. Any help on truck width would help. Thanks! Bob

[DennyB]

Originally posted by Bob Chayer
Hello from NH,

I thinking of the same project but I was going for 4wd. We need it up here in the snow belt! Any idea how wide the truck body is? I need to know if the body will be wide enough in the front to cover the width of the axles. Also I pulled out the tape and found a '71 1/2 axle with 235/75/15 tires and 7" white spoked wheels is 76" from outside of tire to outside of tire. A '72 3/4 ton axle with 265/75/16 tires and stock 7" steel wheels is 78". I think the 3/4 axle is 2" wider than the 1/2 ton by design. I believe a couple inches could be "chopped" of these lengths with different wheels and tires. Not sure if this info helps but I thought I would pass it along. Any help on truck width would help. Thanks! Bob

Bob,
This is what I measured from my 56..
The box is 4'-3" wide with about 12" on each side to tuck tires in.
In the front which is probably more critical, I have 70" in width from the inside fender lip to inside the fender lip.

Does this help?

From the measurements you and Tim (dubie) gave it appears that the 4wd track width is wider than the 2wd. hmmmm

[Bob Chayer]

Thanks for the #s on the body. This has me wondering about wheel back-spacing and how we could tuck the wheels under the body. I'm also thinking about narrow tires and 6" wheels. I talked to my dad who has a 68 3/4 ton 2wd and he is going to send me the track width on his truck. I think the 2wd is more narrow, as I remember his tires are tucked under the truck more than the 4wd. I'll let you know as soon as he gets the #s to me. I am thinking of using a 59 body for the build- up. Any idea if the width of the truck is different from the 55-57 trucks? I think it is the same but it's hard telling sometimes. Thanks again, Bob

[DennyB]

Bob, Read above.
dubie has posted the width of his 59 and the track width of a 71-72.
Any additional width can be made up with backspacing.
The 69 came with drums up front. If you use a 71-72 you get discs for free
A SWB 2wd 67-72 will fit under a 55-59.

[DennyB]

BTW, Whats the width of your 4x4 burb?

[Bob Chayer]

The width of the Burb from fender lip to fender lip is 78". The 3/4 ton set-up just fits under the truck.