http://www.classicrendezvous.com/USA...al_numbers.htm

sorry if it wrapped.

C would be 3rd quarter of 1979, in this case the U is odd.

So 1979 is good, 3rd quarter U could be middle of the month?

There are other small oddities in Masi frame numbering. Things were in a state of flux at the time as far as employees / contractors. Chrome is def. a later thing. That the downtube lacks down tube water bottle braze ons is very curious.