a humble question about the serial number pattern:

we have a lot of Centurions here following the "Letter"-"Number"-"Letter"-- pattern.

Most (not all) have an "N" as first letter - all of these seem to date from the 80ies, right? some have an "M" tho, and these seem to be from the 70ies. Could it be that the letter points to the decade?

i'm asking because on http://www.rennrad-news.de/forum/showthread.php?t=50780
a Centurion(?) emerged with the old style 4-pointed star headbadge, and a very eighties paintjob. It also has Suntour droputs (the linked thread contains pictures)

i'd say its serial# says its 1978... what do you think?