I have never personally used a true trac, but there is a big difference between a true trac and a lockright. The true trac isnt a full locker. Its a lsd. IMHO lsd's are pretty much useless on the trail. When you really need them to come through, your left stuck with only one tire spinning. The lockright on the other hand will lock both tires together like a full locker. It wont leave you with one tire spinning. I just put a lockright in the front of my truck 2 weekends ago, and I like it so far. I havent had any real time to test it out yet (that should change saturday), but it seems to work well. I couldnt really hear it while I was in 4wd, but I could definitely tell that both tires were locked. My advice: If your using it as a dd/light wheeling rig then the lsd may be all you need. If your truck is gonna see more hardcore offroad, then you will kick yourself in the but when 1 tire is in the air just spinning away, while the one on the ground aint doing anything with a lsd. I guess you probably need to tell us what kind of wheeling you plan to do with it.
EDIT- I just saw you said you were gonna do mud and trails and highway. Is this for the front or rear?
-harrison