drivetrain clunk. Need advice.

[Jimmy Pang <jimmyp@xxxxxxxxxxxxxx>]

I recently got myself a used E30.  Initally it had a heavy vibration type
noise from the rear axle when I was in 4th gear (no other gear, only 4th)
and just about balancing the throttle (not accelerating or decelerating,
but giving it just enough gas to keep the engine running at about the speed
the rear wheels were going). Mechanic said it was the gearbox, so we got
that one swapped out with another used one. Sure enough, the noise went
away, but occasionally, going down hill, with the throttle balanced, I can
still hear something that sounds like the driveshaft banging about (like
there is too much freeplay in the shaft/rear axle connection or something).
Also, when I shift gears, I sometimes get a clunk from the rear. Bently's
seems to suggest a driveshaft problem. I'd like to know if anyone's had a
similar problem and what the solution was. BTW, the rear axle was swapped
out with another used one fairly recently too.

Got other niggly problems too, but will wait for a later date to post them.
I would appreciate any light you anyone could shed on this drivetrain
noise. Thanks

------------------------------