The early Series II Scoremasters used a serial number with no alpha-characters -- such as 1004. Later models were alpha-numeric, with 1SC071, 2SC091, and the like. The Arizona company's Servicemasters were similarly serialed: 2SV058, etc. There was a sequence of 1CM150 etc. serials for the Combat Masters. I don't how the Arizona company chose the serial sequences. I don't recall seeing an NM in any of the Arizona company's serial numbers.