You probably need to remove the u-joint or at least the end caps to properly determine the condition. Most of these trucks just used bushings on the caps. Some of the replacements had needle bearings. In any case, if the driveshaft was run for any length of time without oil in the ball there is a good chance that the u-joint is galled. Excess noise, vibration, or movement within the u-joint as a rear wheel is rotated slightly in either direction would be symptoms of a bad u-joint.
