Hello Lads and Gals,
When I studied mechanic, a teacher told us that regarding bearing, if you see something on the race the bearing is shot. If you feel something on the bearing race when running a nail on it, the bearing is double shot.
So IMHO your bearing is just good for the bin.
As per it's replacement and setting the pinion position, carefully measuring the position the pinion has with the shot bearing and setting that measure once the new bearing in place is IMHO sufficient.
Do not forget to change all slip seals on the drive unit.To remove the bearing in the body (to change the seal witch it conceal) put the housing upside down on the bench, and heat the drive unit evenly. When the proper temperature is reached, the bearing will fall with a noise on the bench. To install it, cool the bearing and heat the drive housing. Not that difficult except cleaning the old gasket.... (of course you have a beer can cut properly to protect the big lip seal when assembly time comes from the splines.... )