Poking around the G&L website, I found the following L1K diagram:
http://www.glguitars.com/schematics/...ls_diagram.pdf
Notice that the switch is listed as a 2-position type providing either series (w/ bass boost) or parallel. Also, it appears that they've got the positions listed backwards (with "forward," which I assume means toward the neck, providing the boost mode).
The other thing that's weird is that the diagram is of a back-loader, which leads me to believe this was created long after G&L had been making L1Ks with the 3-position switch.
G&L never actually made an L-1000 without the single coil option, did they? Also, why is the OMG mode routinely referred to as "single coil w/ bass boost" when it's actually series w/ boost?
Any ideas? Obviously, I'm not going to lose sleep over any of this. Just found it very odd that this diagram looks nothing like my '81 L1K's config.