along with what was said above
* the AANJ RG and JEM necks are interchangable
* the old-style RG and JEM necks are interchangable.
Some shimming might be needed, as well as possible redrilling the holes to fit the body 100%. But the neck pocket size and scale are the same.
You can never install an
AANJ neck on an old-style body and vice versa. Good luck... glen