I introduced myself in the New Collector's Forum and have more pictures there.
I read the suffix's were added after the first batch of 10,000 but want to show a picture of my 1937 serial 1288 not showing a suffix:
Here is the serial number preceded by a mark I can't identify:
Can anyone tell me what the mark is to the left of the serial number on the left side of the receiver?
Pardon my moccasins!