I'm just about to glue the neck onto my GSM-1, and thought I better check this before it's too late.
When I received this kit, the truss rod nut was loose and could move backwards and forwards, to the point where it initially looked like I wouldn't get a cover over it. I pressed it back in, and have checked that I can tighten it and put bow/relief in the neck. All seems to be OK, though it does make a nasty creaking sound while I tighten it.