centering rear end

both axles are out a little from stock,you can tell the drums don't sit in as far.When I pulled it apart last year to have the pinion and carrier bearings replaced,I had him pull the thrust pin out,they had left it in.I also took axles to make sure the bearings were pressed all the way on he couldn't move them any more.I will pull them to make sure they are the same and try swapping them side to side.I thought of slotting the holes but figured the perches wouldn't clear the u bolts,have to look at that.It has stock axles, are there diff bearings for stock and aftermarket axles?If I can slot the perch holes I'll have my bro in law weld up the other side to keep it from moving back.Don't want to have it move back or over torque the u bolts.They did,had a hell of a time getting them off,even though they weren't rusty.