Differences between 1/2 and 3/4 T frames (47-54)

[markmdz]

So I know this one has been discussed a few times in the past, but what I can't find is any hard specs. I've read that the 3/4 T frames are more narrow behind the cab than the 1/2 T, but how much more narrow?

Are the frame rails taller as well?

I jumped the gun and bought a Speedway triangulated 4-link kit but now I'm reading that the 1/2 and 3/4T frames are different out back. That's obviously a bit of a problem for me considering I have a 3/4T ('47 3600).

So now I need to determine how much of a problem it really is, or if I could easily modify the Speedway kit to adapt it to my frame.

Any and all help is greatly appreciated.

[dwcsr]

First question is how did you find a 47 3600 in Newtown, I thought for sure they were all rotted to the ground by now. I'm originally from Bethel.

To answer your question not much difference with regards to the installation of the 4 link

Frame it a little taller and thicker on 3600. At the axle the 3100 is 43 " and the is 34"

You have a universal kit so you can put the links where you want, Frame width shouldn't play into it

[markmdz]

Originally Posted by dwcsr

First question is how did you find a 47 3600 in Newtown, I thought for sure they were all rotted to the ground by now. I'm originally from Bethel.

To answer your question not much difference with regards to the installation of the 4 link

Frame it a little taller and thicker on 3600. At the axle the 3100 is 43 " and the is 34"

You have a universal kit so you can put the links where you want, Frame width shouldn't play into it

To answer the first question, the answer is odd. ...I actually bought it out of Millerton, NY where you'd expect it to be more rotted than here in Newtown. ...and... ...yep, it's got its fair share of cancer, but certainly worth saving (relative to other heaps/mudbuckets in this area).

That's great news to hear about the kit, but I fear that this particular kit may not work, as it's a bolt-in kit which looks to have chassis brackets made for bolting within the rails where I'd expect the frame height to come into play.

I'm at a bit of a crossroads too because I just bought a blazer/s10 4x4 rear end w/factory disc brakes because the diff is centered which should make for a much easier weld up of the 4-link brackets. However, I'm wondering if I should have just stuck with the leaf and used an Explorer 8.8 instead.

I'm planning to keep the factory 235 as I have no interest in doing 120mph down the highway. Instead I'd rather just use it as a daily and for local show and cruise night appearances. Eventually it'll also get a Mustang ii (or similar) IFS swap up front too.

[dwcsr]

Bolt-in may make a difference

[mr48chev]

I'd have to look but think that you may be able to set up the 4 link to match the frame unless it is 3100 specific.

Paper page shows the differences in frame rail thickness and height. Basically the 3100 frame is 9/64 thick and 5=3/4 tall by 2-1/4 wide while the 3600 is 3/16 thick by 5-27/32 tall by 2-1/4/

At the rear r the 3100 is 46-1/32 while the 3600 is 36 inches at the rear and pretty well 36 inches from the front cab mounts to the rear. Dang little kick over rear axle on the 3600 though. https://www.gmheritagecenter.com/doc...olet-Truck.pdf

Scroll down the page.

I've got the 3100 frame measurements in this album on Photobucket. the photos aren't the best but you can save them and then expand them to get a better look at the measurements. http://s173.photobucket.com/user/mr4...?sort=4&page=1