8&3/4 axle fitment problem

pressed the retainer to cover the tapered bearing & got 25.75" from flat retainer out to the spline end. OAL 52 & 5/8" (iirc), Moser measured it & said it was stock A body width. I did try an A body SBP (if that makes a difference) 8&3/4 axle & it wont even go in all the way. RR