top number befor ethe milled area is the model id. as I stated.. it ends with 3c.. you can easilly make out 1013c, ie.. first digit is a bit illegible.. etc.
next is date code 2c17b 1972 march 17th, B/day shift ( this means it is a post 68 machine so your model ID first digit is a 'C' if it is a 3000 model.. B if a 2000 modle. previous to 4-68 a 2/3 would have been the first digits
next is the sn..
C denotes a us modle.. and fals into the early 72 sn range as shown in this partial chart of year / starting sn
1972 C327200
1973 C367300
thanks for posting the pic. cleared up all the questions...