Looks like the serial number has long since faded away. Not unheard of. I have a Vantage and the only way to read the SN is at the right angle with the right light. Give it another 10 years and it will probably be gone.
I had a PE-R60 that was the same way. The SN was almost completely gone. I could only make out the fist two number, the others had gone the way of the dinosaurs.
Looks like the PO upgraded the pickups. The PE-1000 came with Protomatic I pickups where the 1500 came with DiMarzios. If you compare the tuners were modeled after Grover tuners which were popular at that time. I'm pretty sure the pickups (except this case) and fingerboard are what differentiate between the 1000 and 1500.
All in all a sweet guitar! I'm
with envy! I have the same bridge on my PE-450 and I absolutely love it! Unbelievable sustain and the intonation will accept just about any gauge strings a player could want.
http://www.matsumoku.org/cm_models/2021 ... ler-slick/