IT IS a shame that Gibson people don't keep an archive of their guitars on their site. SHAME! Fortunately, I have some info on this guitar:
--> It was produced between 1991 - 1996
--> Double-cut solidbody with long horns
(NOTE: The body is exactly the same with the one that Epiphone's EM models have - EM-1, Prophecy EM-2 Custom FX, Prophecy EM-2 Custom EX)
--> 25.5" scale neck (I think Bolt-on) w/24 frets
--> Various PU configurations
The M Series Collection (incomplete):
1) M-III Standard: H/S/H PU configuration, maple fretboard w/black triangle inlays, reverse Explorer headstock w/reversed Gibson Logo (must my inlayed pearl), 1 Tone, 1 Volume, 5-way (or 3-way) blade switch, 1 mini-switch, side jack, Gibson stamped locking vibrato bridge, w/pickguard, various finishes including Metallic Candy Red (don't know the actual finish name) and Ebony.
2) M-III Standard - No Pickguard: The same as (1) but without pickguard, ad shows the guitar in Translucent Amber finish.
3) M-IV S Deluxe: The same model as (1) & (2), but the body wood is different, the finish in Translucent, the vibrato bridge is seems like an alternated/wider Vintage Synchronized Vibrato Bridge, Rosewood (could be Ebony) fingerboard w/triangle pearl inlays.
4) M-IV S Standard: Same as the above, solid Ebony finish, the same weird bridge, Ebony (seems a bit too dark to be Rosewood) fretboard w/pearl dot inlays.
(The ads show the guitars with black hardware)
All these models were produce by Gibson USA.
NOTES:
--> There's a model which had H/H/H PU configuration.
--> Another models had pearl or abalone triangle inlays on the Maple fretboard.
--> I think that some FR style Gibson stamped bridges were made by Kahler (which means the bridge could be either a Kahler Spyder or a Kahler Steeler).
--> Some models were neck-thru constructions.
--> Epiphone produced the EM-2 Rebel, which had trapezoid pearl inlays (Ebony or Rosewood fretboard - not really sure), H/S/H PU configuration, same controls as Gibson and gold hardware.
--> According to the Vintage Guitar magazine Price Guide (2007) the Deluxe models between 1991 - 1992 are valued between $1,500 - $2,500.
Hope this helps, and would someone please tell me if I'm allowed to post pictures that aren't mine (I mean guitar pictures...).