Transmission noise in my '90 V8

[Christopher Olson <ceolson@pclink.com>]

I recently began hearing a harsh metallic buzzing in my transmission
when I start up. I had it checked and found that the transmission fluid
was black and possibly had never been flushed in 88K miles.  After three
fluid changes the transmission fluid has remained red and smells normal.
The transmission functions better now but it seems the noise has become
more persistant.  It now goes away after about 10 miles instead of about
3.  The mechanic suggests that the only hope that the transmission is
not ruined is if perhaps the filter in the transmission is nearly
plugged with sluge and the sound is actually the T-fluid pump starving
for fluid. He suggests that it would be relatively easy and cheap to try
changing the filter.  Does anyone have another opinion?