I have an '88 5-speed 22re 4wd, and I'm replacing the transmission mount. The big nut in the center of the new mount is completely loose, and I'm sure that I have to at least snug it up, but I can't find a torque spec for it.
How tight is the big nut supposed to be?

 

Don't have an exact answer for you but I can say that that nut is only there as a last ditch effort in case the actual rubber parts fail. It keeps the back end of the transmission from being totally free. Under normal conditions it just floats inside its hole and does nothing. You should be able to get it pretty tight and not worry about it. Figure that the threads are about the same size as a lug nut so you can tighten it about the same.

 

I read one thread where someone suggested that tightening it too much would compress the rubber and make it less able to absorb vibrations, so I wasn't sure if I should tighten it that much.
Maybe 50 ft-lbs would be okay? I usually tighten lugs on trucks to 100.

 

I'll have to go back and look but if I recall correctly it's a shouldered bolt so it can't compress the rubber.

 

Or maybe I should just lightly snug it with some high-strength threadlock, if it's just a safety catch.