Have a set for sale, wrapped around a 1980 z-28

 I am sure the 80 Z would have 8.5 gears anyways... That being said, have you tried the aftermarket? They will be much cheaper than the Generals for sure! 

 And just rereading your original post, in my experience, the gears will not have to be from a posi as a set from an open axle will fit as well.

 Let us know how you make out.........