Rear Subframe Main Bolts?
 

I'm trying to replace my rear subframe bushings.

I'm having trouble with the main bolt. The small ones came out easy. The main bolt turns about 20 degrees, but spins the holding plate with it. If the plate is locked in place, the bolt won't turn. It is as if the plate and the bolt have rusted or otherwise locked together.

What is my friend here? PB Blaster? Heat? Great honking breaker bar? What damage am I getting ready to do?

Thanks,
Bob
'82 300D

Definitely sounds like the underside of the bolt head has rusted to the bracket. Leave the smaller two bracket bolts in, use PB Blaster and let it set a few hours. Then get on the main bolt with a good socket and breaker bar.

Update...........
 

It now appears that the center tube of the bushing has rusted to the shaft of the bolt. The bolt turns, but the center section of the bushing turns with it, and the whole thing springs back into place as soon as torque is removed.

With the plate on, I can't get in to cut the center section of the bushing loose -- I can only get about a quarter turn and then it springs right back.

This really sucks..........