they all seem to grind a little when putting them into reverse unless you go from 5th to reverse...3rd gear whining is not good, could be a broken gear or something like that. sometimes they last for awhile something they break right away, i do miss 5 speeds but not for this reason...
they are pretty easy to rebuild if you have done em before, just make sure you do it by yourself or if somebody is helping you not to re arrange the parts when you take them out, make sure you put them in order...
i have been hearing bad things about g-force lately seems everybody is going with liberty so they might be your best bet...they build some good shit i know of quite a few people going fast with them..