It is found on the rather large round flange looking thing that is a part of the pinion yoke.

Anyone know what they are for?

Obviously, they are intended to balance something, but what? The driveshaft?

I just got done doing my rear gears and just noticed them there. I wondered if they had something to do with the vibration I can't seem to get rid of.

I believe its to zero balance the yoke itself. Index mark your shaft to be sure. Vin

Thanks for the info Vin. I know someone around here would be able to help me out!