My mechanic is looking for a leak on the transfer case and says that a stud is turning freely on the rear output shaft. He says my choices are to replace the rear output shaft and thus the stud or to just drive it with 3 bolts tightened on the driveshaft. I have searched and could not find anything related. This is a Lexus dealership that my brother works at and one of their top mechanics. Anyone with similar experience or advice?