I found this article about another, though it is a bolt on neck. Mine is a neck through and also has coil splitters. I've seen one more just like mine, so it's a factory set up.
Onyx Azumi Yamaki Chushin Japan 1979-1982 Maxon Pickups Two Tone Wood Finish
And another ad. This is exactly like mine save for the bolt on neck
$300 · Onyx:Ibanez Electric guitar: Made in Japan
@sambonee, pics as you requested.
This guitar was beat to hell. I've filled the missing chunks with epoxy and sanded off all the PO's horrible artwork of hand painted band names. Looked like a HS kids binder.
I had to make a new brass saddle. I put a strat jack in it because the original was chunky and ugly. Eventually it will get a repaint