Steve beat me to it!
When that came out there had apparently been a couple of drive shaft failures in Monaco motorhomes. If one end comes loose it might flail around and cause a lot of damage! There was a suggestion that with such a short shaft, the U-joint angles are critical and the U-joints have a little more work to do compared to longer drive shafts.
After the bulletin came out, I never heard of any failures. I suspect the real cause was that the failures occurred because the grease fittings were overlooked during maintenance.
They are not easy to grease! My normal hand pump grease gun was useless. I bought a pneumatic grease gun and put a hose and hose extension on it. Then I put a swivel nozzle on the end. With the gun laying on my chest I could get the nozzle on the zirks using two hands. Once on the zirk, I could keep it there with one hand while I squeezed the trigger with the other.
Even harder were the slack adjusters. The corner of a piece of metal was in the way. I finally cut the (useless) corner off with an angle grinder and it got easier.
After you've done it a few times you can see why someone might skip or miss the U-joints.
