U-Joint Noise?
 

I think I finally have exorcised the ABS/ASC demons from my '99 XK8 coupe: rebuilt ABS Module and cleaned and checked wheel sensors.
She has 75,XXX miles on the odometer and runs well except for a noise that seems to becoming more common over time. I would best describe it as a metallic rubbing noise that usually occurs after the car has been driven several miles and begins around 35 mph while accelerating. If I back off the accelerator, it will stop. It seems to be coming from a source under the car, amidship or aft. It is random, meaning it will not always be heard under these circumstances, but it is becoming more frequent.
I recently greased the u-joints in both half shafts and all but one of them took an appropriate amount of grease, overflowing when full, except for that one zerk on the driver's side half shaft that I presume has a clogged fitting or petrified grease.
I am somewhat paranoid about the A-Drum issues I've read about on the Forum and am wondering if a noise as I have described may be an early indication. (The noise is not accompanied by any performance changes -- no slipping transmission -- that I would guess should be an early sign of A-Drum failure.)
Is there some diagnostic a DIYer can perform to determine the source? Any ideas?

When my A drum went out I had been hearing what I thought was a u-joint noise. The problem is the driveshafts don't really make a u-joint noise. All of the symptoms you describe I had when the A drum failed. Sorry to be the bearer of bad news. I did have time to plan, it went out about 3 weeks after I noticed the noise.

Ouch! Vern, I will have to do some more diagnostic work, but I have dreaded the A-drum failure and have been planning to do some pre-emptive work on the transmission: replace fluid and filter and have upgraded parts installed as noted in the Forum. Maybe it's too late for that.
When your A-drum failed, what happened: rough shifts, no transmission engagement, etc?
What did it take to repair it?