8 3/4 489 case pinion bearings

I've been told when swapping gears its a good idea to replace the pinion bearing since it has to be pressed off. I'm just a little confused if I only need to replace the inner or outer or both?

I believe I have a 10 spline pinion shaft as the pinion nut was 1 1/8" as mentioned in another thread on here. Does anybody know what the diameter of that is? The bearings seem to be listed by shaft diameter.

Thanks