Both my 62 and 64 b-bodies with original 8 3/4 rears, 64 is an original 8 3/4 Sure-Grip, do not have the flat top knurl u-bolts.
When I rebuilt the 62 rear I put the flat u-bolts on it, fearing the worst.
Just redid the 64, couldn't find the flat top ones, bought them from Espos along with the...