Well I seemed to have found some issues...
The very first thing I did was jack up the car, put trans in neutral, emergency brake is on (but not working that great..should be fine for this test)...

I twisted the driveshaft clockwise and counterclockwise and it moved about 1/4" each way. Clunked heavily in the pumpkin with that movement. No specs in Bentley for this or...

Front U joint into transmission= definitely loose maybe 1/8" of play. I will certainly repair this first but it seems like only one of two noises. Other two u joints seemed firm. This other noise seems to come from/

I wiggled jiggleed and bounce the wheels up and down with the brake all off and car in neutral but nothing obvious. I know its not thorough as taking the calipers and rotors off, but again, nothing glaring.

Should the gears in the diff make so much noise that I hear them ratt a tatt tatt when I rotate a wheel by hand?

Keep in mind this is quite a POP! I hear and it seems to come from further back than the tranny.

What do you think I should do next?
--
89 245 'loaded' with a Great Pyrenees