[Steeveedee]

Originally Posted by Boog

Look for marks on the drive shaft from things like exhaust pipes, mufflers, parking brake cables, etc. Also remove the torque converter cover and drive it. I had one do much the same and that cover was slightly bent and scraped the flex plate on acceleration but stopped on decel. And sound travels.

That has the earmarks of a worn thrust bearing, though another cause can be the flex plate bending just enough from transmission pressure on the converter.