I'm not sure how many splines my axels and differantals have all 3 of them are open and are 10 bolts with 7.5'' and 7.625'' ring gears.
85' with 3.08's, how many splines on the axel and diff?
85' with 3.42's, how many splines on the axel and diff?
91' with 3.23's , I think it has 28 spline axels and diff.
I need to know what I have because I might swap the axels from the 91 to one of the 85's so I can use an Eaton or Torsen on one of my 85's
I think I can only use the 91 axels on the 85 with the 3.42 gears right? (Then put the 85 axels and diff in the 91.)

 

I can help you out with the axles but not diff sorry man
the two '85's will have 26 spline
your '91 will have 28 spline