With the u-joint uncoupled (first photo below), I dropped the torque tube out of the way. I had a jack stand waiting to support it (second photo below).
I slid the rear u-joint yoke off of the drive shaft and removed the u-joint ball housing off the torque tube (see the third photo below).
Now I can do a little more inspection and I found more clues from the scene of the crime.
In the fourth photo below, you can see that there is some MAJOR scraping going on inside the u-joint ball housing. Not good at all!
I wiggled the drive shaft (called the propeller shaft in the parts book) and found that it could move around 1/16 of an inch is all directions. This could contribute to the u-joint moving around inside its housing.
Next I wiggled the u-joint half still attached to the transmission and found it to be loose! Yes, the cotter pin is in the nut holding the yoke on, but that nut is not tightened down so the yoke can move around another 1/16 of an inch. Hmmmmm.
After that little test, I put the rear u-joint yoke back on the drive shaft splines and found that the yoke was very sloppy on the splines (another 1/16 of an inch of wiggle room). See the last photo.
I will investigate this further after the transmission comes out. At the very least, I need to replace the front drive shaft bushing to take up the slack for the drive shaft sidways movement.
I might need to replace the u-joint yokes. Time will tell. This might be an opportunity to put a 1928 u-joint in Lurch, which has larger bearings. I will explore this down the road.
