If that is rust/staining on the blade, then it was likely made prior to 1980 and has an L6 blade. Even if it is 440C, it was made before 1982-83. The handles on those knives went from gray to black in 1977 and started with serial numbers in the 63xxx range. With a number that low, i would bet on L6. It is highly unlikely that it is one of the later "reissue" knives. Gerber stopped using the forged L6 blades in like 73 or 74, IIRC, but even the "stock removal" L6 models should be somewhat desirable, albeit nothing like the original knives with the canted blade and gray "cats tongue" handle finish. I have a grey handled forged L6 Mark II from 72-73. The sheath also appears to be the old style one like I have, but in black instead of brown/natural.