Not sure if the later mast jacket bearings are different than the AD bearing, but they have rubber surrounding the bear cup. Must have something to do with the aftermarket manufacturing standards but I played hell trying to get the one I got from Chevy Duty in mine.
I went down on the lathe before I installed it and turned up a special driver so as not to damage the cup that holds the bearing. I tried KY-Jelly, Vasaline, Grease, oil, dishwashing soap, and in the end I still had some rubber squeezing out the top and never could get it to seat all the way down to the flange. There was simply to much rubber to get it in the mast jacket. I'd be glad to listen to anyone who believes he has the secret.
In years past when they were avalable, I'd installed the genuine GM mast jacket bearings and never had a problem. When I was a Chevy parts man back in the early 60's I sold a bunch of them and never heard a complaint about how they fit. Just one more thing to add to the list of poorly made after market junk the vendors are sell us.
Denny Graham
Samdwich, IL
