Hello folks,

I have a '92 190E 2.3 with 170k miles.  I'm hearing a short, loud
rubbing noise from the rear of the car when starting from a stop.  It
sounds like someone is scraping the underbody of the car with a
screwdriver handle.  It happens in the first several seconds of the
movement, and never during driving.

I have some theories as to where this is coming from; I'd love to hear
your thoughts on what it could be.

1. Bad differential.  I know mine ran dry due to a leak, and whines at
high speeds.  However, it's not a LSD, so there are no clutches to rub,
and if the noise was caused by skipping teeth wouldn't it happen during
driving too, and sound a little different?

2. Bad transmission.  Maybe the clutches inside the auto tranny are
somehow worn out and rubbing under high torque?  Still doesn't make
sense to produce the noise only on takeoff.

3. Driveshaft rubbing against something.  Could the high torque on
startup cause something to flex and touch the driveshaft?  

Cheers
Alex