Grinding sound in Park

Any suggestions would be appreciated. I have a 440 727TF that has a metallic grinding sound when running in Park. It is a rotational metal sound that does not do it in any other gear. Even in Neutral it is quiet. Has anyone heard of the crank counter weights rubbing on the windage tray?? Engine has some miles on it. 80k or so. This sound just started about 1000 miles back and has been getting lounder. Engine runs fine, idles smooth and no changes were made to it. Oil is clean and I cannot see any filings in the oil. Got me baffled (no pun intended)
Maybe the thrust bearing is worn and crank is moving close to the tray with some scraping?