I bought a used ring and pinion for my Chevy truck. It is a Chevy 10 bolt 8.6". It came with bearings pressed on the pinion and the race for the bearings I bought do not fit. It appears that putting the new bearings on will change my pinion depth. Can I change the bearings, and if so, which spacers do I use? (spacers for my old pinion or for the new one?)

Any help would be appreciated.

Thanks.

Use the shims that are already on the pinion.
If the correct bearing is used to replace the old one, the depth should remain the same.
JA

true, use the same shim

if the new race is different, i would suspect a wrong part. recheck your new parts.

Use the shim that was factory installed in your housing. Most gears are about the same and the bearings are the same within .00005" tolerance but the housings are not a tight tolerance, hence the shim under the rear bearing.