I doubt that the problem is with the motor mounts or the u-joints or any other part of the drive line as all components are relatively new (motor mounts have maybe 30,000 miles; u-joints, carrier bearing & associated parts have about 10,000 miles).

It's interesting that a car in a bone yard had spacers.

Maybe that's the way to go and I'm fretting for nothing.

Thanks everyone.

Are you sure that the noise isn't failing u-joints?

My father-in-laws 240 was making a thunking noise against the bottom of the car. We were sure that was the cause because the rust-proofing gunk was rubbed off where it hit.

I just took off a trans cross member in boneyard car to get the OD solenoid off and there were spacers already between the cross member and body. I was not aware that these cars had these. Maybe they have always just stayed stuck to the body or cross member when I have done this before. This time I noticed as when it fell off it immediately froze onto my hand. They appear to be milled out of aluminum. Maybe you already have these on your car? These were off a '88 auto. There are now sitting in my tool box...

could it be your engine mounts are starting to go. some people also use the diesel ones due to them being stiffer and more HD.