I've posted some photos of the mystery Doug Irwin guitar that my friend bought in the San Francisco area in 1995, shortly before Jerry passed away. We really know nothing about the guitar except that it appears to be a genuine Irwin, it has a brass nut, tailpiece and harmonica bridge, uses Fender amp knobs for tone and volume controls and has a similar looking top to the headless Irwin built for Jerry, so perhaps from that era ... headstock inlay has the eagle and the world, fretboard inlays are similar to the ones on Garcia's guitars. Neck joint looks familiar. At some point there was a Roland MIDI device velcroed below the tailpiece.
The photos are with the strings off and the pickguard loosened, but there was nothing revealing below. Standard Strat wiring.
Here are the shots ... if anyone recognizes it, please chime in:http://leftyguitarsonly.com/doug-irwin-guitar/