Sounds like they’re referring to a center carrier bearing on the driveshaft. At 150k miles it’s entirely possible this is the problem.
A quick look at several parts sites do not show this carrier bearing, or U-joints as being available. This could mean either going to the dealer or an independent driveline shop. The latter is preferred because it will be much cheaper for them to repair it rather than replace the entire unit.
If you live near a major metro area look in the Yellow Pages under “drivelines”.
Regarding the bit about a bad pressure plate due to defective materials, I would take that with a large grain of salt.