I just looked at the 1960 Vehicle Info Kit and the serial number doesn't appear to decipher the month of production like the AD series does. But if 1001 is the starting serial number each MONTH, then it could have been produced in any month of the year. Some clues to the production date would be on rear axle, transmission, and engine serial numbers, which do include the month and day of production. An early production 1960 would likely not have a late production rear axle and transmission, assuming they hadn't been changed.
For instance, my 51's serial number 6JPD 7565 indicates the following:
6=Oakland plant
J = 1951
P = 3100
D = April
7565 = 6565th truck off the line. I believe this number started at 1001 EACH MONTH as the yearly total would be around 150,000 for the Oakland plant which I'm guessing to be roughly correct. Comparing other 51 AD serial numbers would confirm that supposition.
I've seen a '50 2 Ton with a serial number of 9TWE 2893, Norwood plant, 6400, May production, 1893rd truck off the line.
