well, I just figured out the source of the vibration coming from the rear of my car..
turns out that the differential yoke is not spinning "true" which means 1 of 3 things..
either the yoke is worn out of round
the pinion gear is bent
the bearings in the rear are running sloppy on one side..
i won't know for sure untill i pull the axle apart, but while it's apart, and if I do need to replace the 4.10s that are in there... i might go with 4.30 or 4.56 for a little added fun on the street.
the only question is can they be purchased in a "thick" gear for use with a 3.series posi..
i don't have the $$ to even deal with this now, but it needs to be fixed.... and I can't justify swithing posi carriers just for the sake of getting a steeper gear..
I dont' drive long distances on the Highway with the car, so i'm not worried about that.