Hey gang,
Update on this older thread. After 6 months I finally got myself to actually check out the instrument when I dropped of my Lacewoods for appraisal. I talked with Jay Boone, proprietor of Emerald City Guitar, about the guitar and looked it over a bit. Beautiful sounding and looking instrument. The sanding sealer finish gives a very tactile feeling to the guitar very akin to the more recent NENA series of instruments. I corresponded with Gabe about the instrument and he basically rehashed what Tim states above. Jay mailed me a couple of days later that 'that crazy G&L' was sold. And that was the end of it I thought.
Imagine my surprise when a month later I drop of one of my Collings acoustics for appraisal and what do I see on the sales floor? That crazy G&L! This time I was even allowed to take a peek under the pup covers. Played it another time and decided that being given a second chance it was time to take it home, a little cheaper than for the original listed price mind you
And then the fun started: take it apart, photographically document it, send some emails to Gabe again and the end result we both came to is thus:
This
is (one of) the first and one of the few, if not only, surviving HG-2 prototypes which was finished June 3, 1983. That date is written in pen in the spring cavity
under the sanding sealer.
The reason it says SC-2 on the headstock is merely that a SC-2 neck made January 24, 1983, was used for this test mule.

Likewise, the bridge of a '82 S-500 was used, as already stated above.
The pickups are prototypes of GHB pickups used in the HG-2 but with considerably fewer windings. The DC-impedance read 4.10kΩ for the neck pup and 4.12kΩ for the bridge pup.

Steve Reed purchased the guitar in February 1985 in what effectively was a company sale of test mules. You can see more pics of it on
its page on my website, including the weirdest, and clearly non-original, hard-shell case I have ever seen.
There are many more interesting details that I cannot disclose because some gentlemen are writing a book. Oh, that darn book again!
- Jos