[hartbraker]

Replying to your comment about a low rubbing noise in tow with heavy load. The truck in my signature did the same thing. Only under heavy acceleration.

I narrowed the issue down to the flywheel rubbing on the bellhousing cover.

For the life of me, I couldn't figure out what the problem was, until recently. I had the turbo 400 rebuilt, and the issue was resolved. I believe there was too much end play in the input shaft causing the flywhell to be able to walk just enough to come in contact with the cover.

Since having the transmission rebuilt, towing a 20,000 # trailer, I have had no issues.

Hope that helps.