The story: '92 LX 5sp 145K mi. 3:55s installed by previous owner pre 75K mi.
Whine at 40-45mph. Lived with it. Now clunking from diff. Changed the clutches in the t-lok, no difference. When I wiggle the driveshaft, I have about 1/4" play, and can hear the clunking. Anyway to add shims to get rid of the clunking? If teardown is eminent, can I save the 3:55s, or should I get new ones? Any particular brand?
don't know. Mine is exactly the same issue. Rebuilt the Tlok no change. I pulled the cover off of mine and the teeth of the ring gear are razor sharp. I assume the gears are worn. Don't think shimming is going to help-well-it might take away the excessive backlash but is that going to put the pinion too deep into the ring gear?
I plan on swapping to a 3.73 soon anyway so I'm going to live with it for as long as I can stand it.
My worry about shimming is that the gears have already developed a wear pattern with each other. Shimming will put the gears out of alignment with that wear pattern, and then they'll probably continue to whine like that until they develop a new wear pattern, if they even ever do develop a new pattern, which they may not. The damage is already done, the teeth are already deformed, the gears may not be salvageable, BUT you won't know unless you try, know what I mean?
Unfortunately, the RIGHT answer, and probably the answer you will get from a lot of shops, is that you should install a new gear set. This time with proper shimming and backlash.
When you "wiggle" the driveshaft and get a clunk, are you rotating it, or is it moving up and down?
Pinion bearings worn out will whine and clunk. At that point they will also wiggle a great deal at the shaft.