Hi Aaron,
I've checked my M100s, all have white labels and here are the serial numbers:
1389010 type 6309 no overload indicator led, with din concection, stands without monogram.
1380018 type 6309 no overload indicator led, with bi-wire concection.
1612009 type 6319 with overlaod indicator led, din connection and the stands are monogrammed
It seems not all M100's serial numbers start with 144.....
Rudy