The Stovebolt Site Forums The Shop Area Engine Shop 66 Rearend ???

I have a 66 with a 327 and 350 trans. It originally had a 6cyl and three on the tree. The rearend went out and I need some advice. I was told that a rear out of a 72 would work and it would have the six lug too. I don't want to go to five lug. What gear should I use and will the 72 work? Maybe there is a better way I am open to any suggestions.

I'm sure the 72 unit would be longer than your 66. I'd get the original rear rebuilt.

my '66 has a '73 12 bolt rear. it was originally a coil rear truck, so the leafs, mounts, and shackles from the donor truck had to come over too. i think the shock mounting on the frame had to be re-done, as well as relocated shock mounts on the 12 bolt.

i'm still working on getting the parking brake working, it was all pulled off as a v8350/th350 was added at the same time. i think i read elsewhere on the site that you need to pull over the entire brake cabling from the later model.

What you want is a '70 or earlier, after '71 the 1/2 ton 2wd's went to 5 lug.

are the six lug axles from a later 4wd the same bolt pattern? i've heard that they'll swap with the five lug axles on a 12 bolt.

In (mid?)1970 the rearends were widened about 1- 1/2,, 3/4" on each side, the later axles won't fit the earlier rears, then in 1971 they went 5 lug. The 5 lug axles to 87 fit the wider(post 70) rears & vice versa. 73-87 rear end will fit but require the perches to be cut off & coil perches welded on, same for 4x4(they had leaf). Same 6 lug pattern for 4x4(til 98??) & pre-71,,Clear as mud? brian

where in nc are you?

Thanks for the info everyone. Sounds like the best way without extra work and $ is to rebuild...

I'm running a rear end from a '74 or so 4X4 in my '57 GMC half ton. The spring pads were about 3/4 of an inch farther apart than on the '57 axle,but there's enough flex in the spring bushings for it to fit. the total width was close enough to clear everything fine. I had to do the u-bolts differently,I used the newer ones,and the newer speing plates.I had new shock mounts welded to the axle housing and used the rear shocks from the donor truck. I used my original parking brake cables,so that still works too.
My original axle was a 4.10,the replacement is a 3.08-almost TOO tall for the 270.
My point is that the differences from '57 to '74 axle assemblies are few enough I consider it a bolt in swap.
Speed