building 8 3/4 489 section

I recently replaced the 5.13 gears in my 8.75, broke of 2 ring gears teeth after 30 years of 4 speed street and strip (slicks). the factory service manual does not say to check the diameter of the bore for the carrier bearing races. I noticed slight spinning of the races in the carrier. the outside diameter of the races measured right on at 3.250", the bore measured 3.253". I sanded down the cap faces to get the bores to 3.250". when parts are banging around-they break