Cameraflage,
From what I've been able to hunt up, every MH-6C I've been able to find info on (which wasn't many) IS a Vietnam-vintage bird. So far, I've found two 1969 tail numbers, and the bird above was originally OH-6A 68-17249 and was in Vietnam from September 1969 through January 1973! She served with D/1-4 Cav and then C/16 Cav in the Mekong Delta. By 1975 she was turned over to the National Guard, and I guess was converted to MH-6C standard by the time the Guard stopped operating OH-6s in the mid-90s.
Interesting though, while most helicopter remanufacture gives the bird an entirely new tail number, upgrade to MH-6C standard retains the original number.... I wonder why?!