Re: Info on RG520IX?
Well, that's obviously a JPM-style control layout, but the controls aren't positioned quite right for an authentic JPM (too close together, shifted toward the bottom of the body). Not sure where the neck came from with no inlays, but of course a JPM would have offset dots in any event. I'd say someone went a little mod-happy trying to build a JPM replica off an RG520 base.
Not sure where the "IX" in the stamp comes from, where does this appear, the neck pocket? Possibly someone more familiar with deciphering these seemingly inconsistent codes could help out here.