1985 BMW 528e noise when driving?

Noises problem
1985 BMW 528e Two Wheel Drive Automatic

Hi
new here and would appreciate any suggestions. My car is making a strange noise somewhere between a thunking and tinging noise. This only happens when the car is in motion -especially when accelerating? It is coming from the right rear area. We have looked under the car as it is driving and nothing appears loose, have climbed under it and can see anything that could be making this noise, it does not do it if we are at a red light or stop sign. There is no noticeable pulling to either side. If there is anyone who knows what this could be -any help would be very welcome!
thanks so much!