[Mike C]

Most GMC trucks had the Dana 60 while most Chevrolets had the HO5200. But they can be found either way depending on what combination of factory options, what factory it might have been put together at, or what some "junkyard engineer" has swapped in!

The full-float setup on the Dana 60 8 lug is more heavy duty than the semi-float setup of the AAM 9.5" rear. But they are both factory rated to 5500#. Unless you load your truck way over rated GVW you are good either way.

If you can find the right gear ratio (3.23/3.42/3.73) with a Gov-Lok already installed, expect to pay about $200-$250. Less probably at a pick-ur-part. Brackets set you back about $50-$75. Then installation which will depend on how much cleaning, grinding, fitting, and welding you can do yourself.

Same is true of a Dana 60 though. If you can find a 3.54 setup with a TracLok then you are good to go. Some had PowerLocks as well and that would be the ideal setup. Most are open diff IME but that's limited to only a few trucks and they have all been 1970 GMC's. The 4.56 geared PowerLock equipped Longhorn I bought for parts had an open 3.73 gear set in it, so you never know what a PO did relative to the SPID.