Squeal on 87 5000sq

[smarks@ns.net (Steven N. Marks)]

Hey:

Can you help me out?  I have an 87 5000sq with 124,000 miles (great car).

For some time now I have had a "squeal" (def. a high, shrill cry or sound)
after rain or a trip to the auto spa (car wash).  The sound is typically
evident while in first gear, starting off from a dead stop.  For that
matter, I hear it while backing up in reverse.  Not consistent, so it is
hard to share this charming sound with mechanic.

And you thought you had heard everything.  Any ideas?  Thanks in advance.

Steve