Trunion and ball

One way to "test" the B&T is to remove the coupling flange at the trans. Put 2 or 3 flat washers on each stud, and reinstall the shaft. If that cures or reduces the problem, your joint is bad. Don't leave it that way. This is just to test the joint. If the boot is ripped, and the grease is gone, the joint is shot.
https://earlycuda.org/techdocs/ConvertFrontUJoint.pdf