Using old bearings as "Setup" Bearings

What is the concensus on reeming out old carrier and pinions bearings and using them as "setup" bearings? It seems like alot of money to ruin a good set of new bearings to make setup bearings. Would using the old bearings be accurate for setting up the pinion depth, pinion preload, carrier preload, and backlash?

IIRC, no. you need identical bearings and races for proper setup.

Old bearings in good condition would be okay for setting depth, and shim thickness for the carrier, but I wouldn't use them for setting pinion preload. That should be done with the bearing you're actually going to be running.

I agree the old bearings are onlty good for the for the pinion depth. If you use the old Pinion Depth anyway, you shoudl be real close.

I always use "setup" bearings for setting up new gears.
They work great and speed up the process of getting within a few thousands of a perfect setup.
Once you're real close, simply switch to the new bearings for the fine tuning, and you only have to press off the new bearings a couple of times to get it perfect...