About a month ago I swapped in a 3.73 posi rear and noticed when I took it for a spin that at higher speeds when on the throttle, the differential seemed to whine. If I let off the throttle, the whine went away. Crap.

Replaced my old steel driveshaft with an aluminum one the other day and noticed that there is gear oil leaking from where the driveshaft meets the rear differential. I looked up some info on the subject, and I'm thinking a bad pinion bearing? I hear a leaky pinion seal is a tell-tale sign of a worn pinion bearing. Any help is appreciated. Any info on the steps involved in fixing this would also help. Thanks.