changed pinion seal,roller bearing,cup at the rear diff. that stopped the leak out the frount of my diff. however there is a real high pitch whistle comes and goes. it winds down as you roll to a stop. seems to laouder when car is cold.( wish you could record sounds on here ha!) help.

 

Not sure what make ort model you have, but it may be the parking brake shoe(s) or rear brake pads. Just a guess.

 

I've just noticed the same problem with my '86 240DL. Sounds like a police siren off in the distance. It winds down and then repeats itself once or twice. It's got me looking in my rearview mirror to see if I'm getting pulled over. Symptoms are pretty close. The car is cold, ambient temperature here was in the teens, and normally occurs when I take my foot off the accelerator, but does continue when I put on the brakes. It does not seem to be speed related, as it occurs on city streets, slowing down from 25 mph as well as on country roads, slowing down from 50 mph. It seems to go away after the car has run for about 4 or 5 miles. I'll be keeping and eye on this for a possible remeady.

 

mine's an 89 gl sedan auto, maybe tourque converter? transmission

 

Seems to me it's coming from behind me, not below me.

 

Make sure the Driveshaft bearing isn't seized. I have seen them seize up and spin in the rubber housing and make a noise.