Differences in GMC and Chevy Frames?
 

I am trying to find out the difference in the GMC & CHEVY frame. I know that the GMC has a leaf spring rear but are the front suspensions the same and the other body parts interchangeable. I want to shorten the frame to make it a short bed and trying to figure out if the articles I see on how to do it close enough or should I figure something out myself. Thanks, John

Re: Differences in GMC and Chevy Frames?
 

When I did the "restoration" (or "restomod" or whatever you want to call it) on the green '66 you can see in my avatar, John, I had the long bed frame shortened to be able to put a short bed on it. If you're wondering if a Chevy short bed will fit on a GMC frame, it definitely will because that's what I did. I had the first cut made straight down from the back of the cab and the second cut made 12" to the rear. The joined sections were reinforced with "fish plates". Another 8" was cut off the tail ends of the frame rails. Then the Chevy short bed bolted right on using existing holes in the GMC frame. Hope this helps!

Re: Differences in GMC and Chevy Frames?
 

So I so not have to remove the cab and move the cab mount. I looked at it and cannot figure out why I saw an article where they cut it under the cab and then moved the mount. Saw no reason why it was do that way. Thanks for the info. I will post photos when done.

Re: Differences in GMC and Chevy Frames?
 

There's definitely no need to remove the cab nor move the cab mount, John. The cab on my '66 (now owned by Clyde in SC) was never off the frame. Good luck with your project!

Re: Differences in GMC and Chevy Frames?
 

Thanks, for you most informative information. Truly is a time saver. John

Re: Differences in GMC and Chevy Frames?
 

It should go without saying, though, that you should check the dimensions on the frame and bed you're working with before making any cuts to confirm that what I did works for you as well.

Re: Differences in GMC and Chevy Frames?
 

I don't have my book in front of me, but didn't leaf-spring trucks and coil-spring trucks have different frames?

I know the coil spring trucks have an X frame. Didn't leaf-spring trucks have a ladder frame?

B

Re: Differences in GMC and Chevy Frames?
 

I am not sure about the ladder bar suspension. But I am going to someone's house this weekend who has a Chevy frame and I will check. It is a bare short bed frame. Figures after I do the work I find a frame. I am going to buy it just to have it if I ever need it, John

Re: Differences in GMC and Chevy Frames?
 

I just got my book out, and I was correct. 4wd (leaf spring) trucks had ladder-bar suspensions while 2wd (coil spring) trucks had x-frame.

B

Re: Differences in GMC and Chevy Frames?
 

Differs by year though.
Torsion bar front/coil rear are early (1960-1962)
coil front/leaf rear are later (1963-1966)

4 wheel drive is another (3rd) frame type.

From the club page:
http://6066gmcguy.com/GMCvsChevy.html

GMC:
1960-62:
Torsion Bar Front, Most all Models
Coil Spring Trailing Arm Rear - 1000, 1500
Leaf Spring Rear - 2500 & Larger
1963-66:
Coil Spring Front, 1000, 1500 & 2500
I-Beam Front Axle - 3500 & Larger
Leaf Spring Rear - All Models
Some Larger Trucks had Air Ride Springs.

Chevrolet:
1960-62:
Torsion Bar Front, Most all Models
Coil Spring Trailing Arm Rear - 10, 20
Leaf Spring Rear - 30 & Larger
1963-66:
Coil Spring Front, 10, 20 & 30
Coil Spring Trailing Arm Rear - 10, 20
I-Beam Front Axle - 50 & Larger
Leaf Spring Rear - 30 & Larger

Re: Differences in GMC and Chevy Frames?
 

I would *guess* that would be for the early frame, 1960-1962 with the coil spring rear and trailing arms. Most likely due to where the trailing arms pivot from on the frame.

You can see that the pivot point on the early frames is just forward of the rear of the cab, (forward of the rear cab mounts) so you would have to cut the frame under the cab to shorten it, unless you wanted to get into cutting and re-engineering the trailing arms **if you had a 1960-1962 frame**

http://oldcarbrochures.org/var/album...g?m=1305516845

Re: Differences in GMC and Chevy Frames?
 

Also, the '60-'62 trucks could be ordered with leaf springs under a rpo (regular production option). My grandfather ordered all of his 60-62 1000-1500 series trucks with them, only after receiving the first few 1960 mdls with the coil spr rears.


Cordially,
Lewis Ellis Matkin, Jr.
Ridge Manor, Fl.
1965 1002 305E