sentences:  Original Mk1 examples are prized and in particular, "pre production" examples from the first half of 1976 together with the "end of line" special editions from 1983.The MK1 Grifter dates back to May 1976, although this pre-mass production version of the bike is quite rare (frame numbers starting with NG6).Main production started in June 1976 and continued until 1979.