What chassis do I have?

[Sevens]

I have a 1965 GMC 3/4 ton truck...that's what the VIN number tells me anyway...

At some point in its lifetime, someone did a 5 lug swap and drivetrain swap; it has leaf-springs in the rear. I believe everything that was swapped was from a 1975 C10 (based on casting numbers and the PO's story).

I plan on lowering the rear-end a few inches.

I don't want to buy parts and see if they fit only to find out that they are wrong.


My question is this; is there a difference between a 1965 chassis and a 1975 chassis...and if so, how can I tell which one mine is?

[mongocanfly]

Are you asking about the frame?...I would suspect a big difference In the frames..are cab and body mounts stock looking or homemade looking?...is the rear soa or aos?...if aos ,then a simple drop block and ubolts would do it

[Sevens]

Originally Posted by mongocanfly

Are you asking about the frame?...I would suspect a big difference In the frames..are cab and body mounts stock looking or homemade looking?...is the rear soa or aos?...if aos ,then a simple drop block and ubolts would do it

Yes, the frame... The mounts all look stock; but I'm not sure that is definitive.

It is soa, so I can't do blocks and U-bolts.

I've been searching for a bit and haven't been able to find any definitive way to tell them apart...I'm hoping someone on here has the answer!

[mongocanfly]

If all the body mounts look stock to the frame, then most likely they did a drivetrain swap...can you get pics of the drivetrain parts and mounts?

[Sevens]

It looks factory to me for the most part.


More photos:

Driver side body mounts:

The bracket is riveted and looks stock...but why are there two sets of holes?


Leaf-spring mount:


Rear-end:


Welded-on shock mount:

[Sevens]

I had big plans for this truck this year but unfortunately I got laid off about 3 weeks ago. I am going to have to hit the pause button for a while on the "big" stuff.

[cwcarpenter98]

Most GMCs came with leaf springs in the rear from the factory. Do the front frame horns match the contour of the bumper?

[mongocanfly]

From what I can see it looks like your on a stock frame,,, but the rear axle has been swapped...
For a quick easy/cheap drop in the rear , you could pull a couple of leaves outta the spring pack..
It will affect ride and hauling, but if those are stock 3/4t springs it may not matter much....
Drop springs would be the ideal way to do it though....

[Captainfab]

That is your original frame with a 12 bolt swap likely from the '75 donor. GMC's came standard with leaf springs.

[Sevens]

Originally Posted by cwcarpenter98

Most GMCs came with leaf springs in the rear from the factory. Do the front frame horns match the contour of the bumper?

I never thought to check the bumper.... Yes, it matches the contour. I think that answers my question! Thanks Chris.

Originally Posted by mongocanfly

From what I can see it looks like your on a stock frame,,, but the rear axle has been swapped...
For a quick easy/cheap drop in the rear , you could pull a couple of leaves outta the spring pack..
It will affect ride and hauling, but if those are stock 3/4t springs it may not matter much....
Drop springs would be the ideal way to do it though....

I was thinking about a shackle extension to drop 2". I think that would allow me to keep the same ride-quality.

Originally Posted by Captainfab

That is your original frame with a 12 bolt swap likely from the '75 donor. GMC's came standard with leaf springs.

Thank you, I appreciate the input!


You guys rock!

[mongocanfly]

How much clearance do you have between the spring eye and the bed floor? It looks fairly close in your pic..
A drop shackle may also change your pinion angle some...

[Sevens]

Originally Posted by mongocanfly

How much clearance do you have between the spring eye and the bed floor? It looks fairly close in your pic..
A drop shackle may also change your pinion angle some...

I will have to measure it...but this camera angle is deceiving. There is more room than there appears from this angle.

I will probably just buy the leaf springs either way.

[lobuck64]

Hey I got 65 gmc swb used 76 rear axle used flip kit for 73-87 still using original springs replaced bushings and hangers tried to upload a picture but would not load send me a pm if you want info on bushings and hangers