It's a 1990 740 manual turbo intercooled wagon.

Empty, the car runs great. Loaded, or up a hill, or boatramp, you get this terrible grinding sound like a bad bearing or I don't know what, especially in 1st and reverse. It doesn't take much weight.

I loaded some batteries in the back and took it to the shop so they could hear the sound. We drove around, they heard it, said "transmission is fine, sounds like a bad center support."

I left it with them. They called and said the bolts on my center support were loose, it was fine otherwise. They charged me $30 for their time to diagnose and tighten. They said they checked the whole driveline, everything is fine, and then the baffling part, they said that lots of 740's make this noise and there is nothing to be done about it!! What? The car does still make the noise, it might be better, but it's still there.

Are there any noises that 740s are known for making? I'd like to keep hunting but a little daunted on how to find the noise since it is only apparent under loaded conditions, which are hard to replicate with the car jacked up, etc.