Another thing is the type of posi carrier. Every '68 8.2 posi rear I came across had worn out cone clutches. You can get brand new ones but that will cost a bundle, and they are still not that good. Meanwhile the 8.5 rears used disc clutches, which last a lot longer and are much easier to get parts for a re-build. Every 8.5 I have ever seen the clutches were fine. Even used 8.5 posi carriers from Gevo were in great condition, not needing a thing. On top of that, the gears sets available for the 8.5 is extensive, while the 8.2 in very limited. Do a simple search on this site: Yukon Gear I know it is a lot of work to adapt an 8.5 to a first gen, buy in my opinion, well worth it.