I have been reading the LMC catalog and the ads in Cl***ic Trucks magazine looking at the availability of parts for my '62 shortbox. For some reason they never mention lowered springs for the rearends of '60-'62 trucks. Why is that? Are they different? Not that it truly matters to me since I plan on using similar p***enger car springs (just shorter) on the rear. A buddy of mine did that to his truck using '71 Chevelle springs on his. Enquiring minds want to know.
strange....although the rear axle is completely different, I'd think the springs woud be similar. maybe you could show us a pic of what yours looks like under there? I have a 64 rear frame section to compare.
Not quite. The 60-64 used a large bracket on the right side axle tube to anchor the panhard bar. The 65-72 used a stud atop the center pumpkin to anchor the panhard bar. The rears got 1.5 inches wider in mid 70. In 71, the bolt pattern changed to the 5 on 5 common GM truck pattern. The 5 lug 71 or 72 axle shafts will interchange into the late 70 model rears only, due to their added width. You can interchange the 5 lug axles into 65-early 70 rears by fabricating 3/4 inch thick spacers to go between the brake backing plate and the axle tube flange. This is not recomended though, as the axle bearings won't ride where they are supposed to on the axle. Early axles used different spline count than the laters did. 64 was the break year if I remember correctly. You can swap a 65 and newer rear into the earlier truck by using the later panhard bar and panhard frame mount bracket along with the newer rear in the older truck. The panhard frame mount rivets on with 4 bolts. It's a direct swap other than the hell of removing the 4 rivets and bolting the newer one. on.
great info! but what does it have to do with the springs, which sit between the frame and the trailing arms?
I was elaborating on Flat-Top's post. It's good info, some folks may use it, whether it's directly related to the question or not.
Hmm, I did not realize the 71-72 rear was wider. Not exactly a direct bolt on. If I wanted to convert a 60-66 rear to 5x5, can it be done? If not, which late model fits best?
One of the biggest reasons that lowering **** is so hard to find for 60-62's is that the frame is different than on the 63 and up. 60-62 trucks had a much thicker, heavier frame. I think that the springs themselves will work, but the lowered shock mounts, etc. that everyone sells won't, which I think is why they just advertise the springs as '63-up. I found this out talking to the guys at Early Cl***ic Enterprises when I wanted to know if the stuff my dad had bought for his '66 would work on the '62 I had. If you don't want to make up your own shock mounts, one solution might be to go with a pair of Slam Specialties [at least I think that was the name] airbags. They're more rigid than normal bags, so they can be run without shocks. That was just one of the things I was thinking of doing.
Thanks spent, that is awesome information. I'll probably fab my own shock mounts, I have access to lots of s**** metal. Tell me about other stuff you did to your '62!
To jump into this old thread with just a little bit of related info... I believe the rearend TYPE itself is different from mid (I believe) '63 on back than for the late truck 12-bolt which was mid-'63 up. At least I think the change was MID '63, but I'm not an expert on that. Pretty sure the rearend TYPE was different prior to '63, though. I once installed a '65 rear into my '63, and yes, the bracket for the panhard bar was different. I also had to use the '65 panhard instead of the '63 bar... they were different lengths. Also, note that the '63-4 rears had 17-spline axles. I think '65 went to 30-spline. I remember replacing only ONE axle in that '65 rear, and I know it was 30-spline, because I installed a brand new 30-spline Eaton posi in it. Hope that helps a little.
Another thing to bear in mind is that GMC's in these years used leaf springs in the rear instead of the coils. Alot of people ***ume whatever works on a Chev will also work on a GMC and it's not always true.
Not 100%, since coils were optional on GMC and leafs optional on C-10. 60-63 used the old style round chunk, then went to the Truck 12 bolt. I have a '68 rear and had the axles redrilled 5 on 5, since I have a 3.73 Posi.
yeah, same 3rd member, different housing, not sure about axles, I could look it all up if you'r interested
Good info, thanks guys. I saw on another 60-66 forum that rear Jeep TJ coils will swap in the back and give 3" drop. I picked up a free set from my local 4x4 shop today and I'll post when I confirm it.
I believe that early rear changed to the late truck 12-bolt in mid-'63. I had the late 12-bolt in my '63, and I was only the second owner (bought it from the original owner). That truck also had alternator (instead of generator), which I think was factory-mounted. I think mid-'63 they started doing some changes.
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