Not many of these around. Unique Gibson MK-35
Believe this is a 1975.
Between 1975 and 1978, Gibson produced the Mark series of flattop acoustics which were designed by Michael Kasha and Ricahrd Schneider. These steel-strings had a 16 3/16-inch wide body and were narrower at the waist than a normal dreadnought. The MK-35 specifically used Mahogany for its back and sides, dot inlays, nickle-plated, and a three-piece Rosewood fingerboard.