Unknown model 8
Thanks to David Smith for the pictures and info on this one. He bought it in 1984 (Date of manufacture not known, there is no serial number), and was told that it was a prototype and there were only about 10 made. Looking at the top of the body, the natural conclusion is that it's a Prestige 250.....
... until you see the rest of it. Only 2 knobs, one volume and one tone, a Thunder style brass bridge, and a gold coloured mini toggle switch for active on/off (Paduak style boost, not active tone controls - I suspect this is actually a coil tap switch, see the black one below)
Then you see the headstock....
Same style as the Concord series, but with gold hardware and a brass nut, and no model name. The neck is bolt-on. It is possible that Matsumoku were considering adding a 'Prestige' model to the Concord range.
Or more than one model - this very similar guitar appeared on Ebay (UK) in December 2009 - thanks to the seller ingenue1982 for the photos. The heastock logo and neck plate design would seem to date this guitar to pre 1984. There are 3 differences between this and the one above - the finish (Black on this one), this one has bevelled edges on the heastock which the one above does not have and this one has chrome hardware. 21 frets, two humbuckers, single volume and tone controls, pickup selector switch and coil tap switch.
Both of these guitars are missing something that I would expect to see on any production guitar, which may support the theory that these are prototypes / concept guitars. See if you can spot it (Or rather, not spot it) on the photos of the fronts of the guitars. Send an email to uk8@westone.info if you have an idea