This was taken from a post on North Carolina 4x4 forum. "SM 420s like to wear out the shift rods and fork assemblies long before the gears and bearings are gone, especially if Billy Bob driver liked to hang onto the shift lever like a grab handle as he went 'round corners. The detent balls wear the lands on the rods leaving a depression rather than a true detent and the shift forks wear to the point of sloppiness, failing to fully engage the gears. Try that first, it's a relatively cheap fix if it works and you're ahead on the parts if there's more to do. Be aware that if the detents are really worn, there'll be more stuff that needs attention." I just figured you guys wouldn't mind me posting up this good piece of info.