Thanks for the u-joint tip. I will check them out pronto.
I can find no positive I.D. on my axle, but I'm sure you're right about it being a D44. What fooled me is that my service manual shows a D44 as the front axle but a D60 is the only Dana unit shown for the rear and, yes, it does at least say "limited slip" on one tag, "3.31" on another tag and "Dana" all over the place.
I will check the splines on the wiper crank and for linkage slop. In other (non-Jeep) vehicles which I have, this problem has usually been electrical in nature. Thanks for the pointer.
1988 Jeep GW