Probably designed for drag racing only back when originally designed and sold
OP, I put a set on a Dana 60 rear end years ago (1970 35 spline axles) that was driven on the street and the inner retainer came loose and let the axle slide out of that bearing until the tire touched the outer wheel lip
Same thing happened to another Dana 60 that was in a drag race only car at the track Both of those where the first type Green ball bearing axle bearings for Mopars offered back in the mid 1970s, I have sold, installed and used the newer ones like Dr. Diff sells now with no more problems
The early ones had the retainer molded onto the bearings, the later, better, ones don't The retainer is not captured on the bearing and the later ones have a retainer ring on the outer bearing race on the axle end to locate the bearing in the housing on all the newer ones I've used in both 8 3/4 and Dana 60 regardless of axle size or spline count