I have 2 O-type 12-bolt rear ends and I'm trying to figure out what to do. First I have a 1968 posi o-type 12-bolt that needs bearings and a 1970 non-posi 12-bolt o-type rearend that needs nothing. Does the guts from the 68 fit into the housing of the 70? Any advice please provide input!

 

No expert here . I think they will need to know gearing on both axles to see if all parts need to be changed out or just the posi unit
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Does your 68 have 31 spline axles? 70 have 28, also I think the out seals are different,68-70

 

yeah the seals are different, I'm not sure what the splines are on the 70 I haven't pulled them out yet. The 68 has 31 splines but I still need to pull the shafts on the 70. I was wondering what the difference was because the 70 is set up already and all I need to do is redo the brakes and add gear oil and it'll be ready to go, the only issue is that it's not posi. I was wondering if that is a smart move because the 68 I can buy for 100 and guts are 3.42 posi. I'm planning on building a 496 BBO stroker in the end.