8 3/4 489 case pinion bearings

As long as it's pressed off correctly and the bearing is good there's no need to replace it IMO. I've reused them with no problems. The bearings are specified by case so you order them for a 489 case. They were used starting in 1970. Here's a chart showing the bearings and part numbers for 8-3/4 rears.

8 3/4" 3rd member bearings.

741 case
Differential 57-early 69: 25590/25520
Differential Late 69-74: LM104949/LM104912
Pinion inner: HM89446/HM89410
Pinion outer:M88048/M88010
Seal: 8515N

742 case
Differential : 25590/25520
Pinion inner: HM803149/HM803110
Pinion outer: HM89443/HM89410
Seal: 7216

489 case
Differential: LM104949/LM104912
Pinion inner: M804049/M804010
Pinion outer: M88048/M88010
Seal: 5126

You should be able to take these numbers to most any parts store and get them.