I was my car (1981 300 SD) back from school, and sped up to about 75 (I've done this many times before), then a turn was coming up so I left off the gas a little (No big deal), took the the turn, and about 2 seconds later I hear this click click noise, and it gets more frequent. So I pulled over, and looked over the outside of the car, and nothing seemed out of wack. I drive home, the clicking persists, until it seems like it's almost a whirling (water like) sound, I get about 5 minutes from my house, the sound dies down a bit, then within a few blocks of my house the sound is gone. Then I drive my car later on in the evening, the car makes no noise, until I drive it at about 40mph, then the clicking slowly begins (Then proceeded with the swirling sound) and keeps going until I drive the car about 30 mph for a half a minute or so then it stops. The sound itself really seems like it's coming from the area underneath the armest, yesterday I took out the center console (Nothing wrong there), today I took out the instrument panel and whatnot so I could get a good glimpse under the back of the console, (nothing strange there) The car is going in the shop soon, however I'm wondering if you guys could give me some advice as to what it might be (Some kind of bearing?), and if it is safe to drive (since there it doesn't affect the way the car handles at all) Thanks a lot, I really appreciate the help. Sorry for the long read

I had a bad center driveshaft support and it made noise just under the center console. Put your hand just behind the center console (hump in rear floor) as it is making the noise and see if the vibration can be felt in that area.

Thanks Q - I took it out to see if I could feel the vibration, and I couldn't.

And then as I was driving the same road as last night, the sound started at about 45mph, then started getting louder, and then I moved the rear part of the console around, and it stopped for a bit, then started back up but much more quiet than before (And at another point when I moved the console area around some more it stopped again). Even when it did start back up, even at 65 mph, the sound wasn't very noticable anymore.