My rear differential pinon bearing seal is leaking. My mechanic took it apart and indicated that I could get away with a new seal and a new yolk (the old seal had worn down the sleeve of the yolk), but to be certain the bearings are OK, he would need to dismantle the diff to inspect and replace... a much more $$$$ job. My runner has 122K on it. Can anyone give me input - should I have the rear bearings replaced, or can I get away with just a new seal?

1999 SR5 V6 4WD
Addcos, Bilsteins, Detroit Truetrac, Amsoil, etc...