vibrations- something hitting metal

[ned2683]

1984 300SD

a couple of month ago i had the car parking for a week while i worked on a suspension issue. once i got it up and driving again i had this weird noise. sounds to me, and i thought it was that the exaust was hitting the inner body. its a knocking noise. its not constant, more loud at some RPM, and when i turn one direction or park on a hill. for example when i shift i will usually hear a couple of knocks. i ran my hands along the exaust and couldn't find anywhere that it could be hitting, but this was with the car in park.

after about a week of this it went away, completly!

last week i had the car worked on at a shop (guide rod mount), when i picked up my car it started again, they had it parked for 2 days before i could pick it up! not as bad as the first time but i don't know what it could be. its hard to hear it from outside, but it seems to be amplified in the interior. from what i can tell its coming from the right side of the radio (passanger side) of the transmission hump or around that area.

can anyone point me in the right direction?