I jacked the rear end up and put on jack stands and then slipped the transmission into first gear, was checking a wobble in left rear. Should both rear tires rotate at the same rate of speed?
no they wont , if one wheel drags a little the other will turn faster, on a turn one wheel will turn faster than the other, if one wheel is stopped completely the other will keep turning
While you're working on the rear wheels, tighten the axle nuts so you won't break an axle. Use a long breaker bar. You can't over tighten them unless you really are Superman.