Auto Trans Question

[daffern1]

I only drive our 69 280SL infrequently. After the car sat for a couple of weeks I noticed when I put the transmission in "2" or "3" with the car stopped it made a noise almost like a bearing going south. It was also noticeable when moving forward at very low speed but went away when the speed picked up. When I put the trans into "N" or "R" the noise went away.

I hate to ask, but any ideas on what might be going on?