I have the same problem The u joints started binding and then destroyed the rubber around the center support bearing. Whenever i would accelerate it would rattle and i could feel it below the shift tunnel.
They are staked for sure and one look at mine I decided its going to a driveline shop.
The driveshaft is also balanced with a weight welded onto it. Make sure to mark where it is before seperating the two halves if you do the work.
The same symptoms and in my case its a matter of both u joints, a center support bearing, and a new guibo for peace of mind.
both of my u joint sections will only pivot one direction without major resistance. The other side is completely bound up and dry on both.
mine went out at 180k -190k miles with 135k of that supercharged so your's lasted quite a bit longer ^^ |