Go ahead and fix it, it's simple. Don't limp on it when you have the parts to fix it. And, I don't know about the torque mount. My t-case and frame both have holes for a torque mount bracket, but there is none. I thought I was missing some thing and scoured J/Y's for a bracket, then read on this site that some trucks have 'em and some don't. I guess it's not a big issue. But, if you do have a torque mount bracket, I guess it wouldn't hurt to replace it, if it's shot.
Kharmanghia- I, too, have had perpetual u-joint failure. The first time was about a month after I bought the K5. Then, I'd get maybe 1000 miles out of a u-joint after I changed it. It was ALWAYS the joint at the output of the xfer case. And, always the trunnions under the u-bolts where it mounts to the case. Turns out I was torquing the nuts down too tight, they only require 15-20 foot pounds. I was cranking them down nice and tight. After I applied the proper torque, with lock washers and loctite, they have been good. After a good look at the rear transfer output yoke, I think that may have contributed to the problems, so I changed that. Make sure your driveline angles are good.