Dusty Ratcliff

my 5th gear nut backed off again over the weekend, after I got it apart today I noticed the nut didn't have many threads left in it, & upon further inspection noticed the splines were worn really bad inside the nut, then checked the mainshaft & the splines are pretty much shot on it too. Looked on quad 4x4's website at the torque king mainshaft kit, & was wondering how hard of an install this is??? and is this my best bet or are there other options out there??? thanks, Dusty