rap/clatter park only? 1998 2500

1998 ram 2500. I'm getting a steady clatter or rapping from area of torque converter. It is only present when in park. If you put it in neutral or D,R etc the noise stops. I know the fluid does not circulate to the cooler when in Park, is there a valve or solenoid, or check valve that could make this sound? Thanks any info on this and thanks for past info.

I just bought this truck and am working my way through a few quirks and puzzles. My last Dodge was an 82Ram no frills, so this one is a tad more complicated.

The converter inspection cover was pushed in and was being contacted by bolt on the converter.