im voting for differential fluid. Or tranny fluid.
My e30 had a whinning at speed(55+) that i could not figure out. Turns out the sound was from old diff fluid.
try that. its a cheap and easy fix. If it works then great. If not you still have new Diff fluid.
We all get the urge...Saturday early morning...nothing to do till noon...
The aural sensations of 1st gear WOT
**CGM **(Certified Garage Mechanic)