[Edward Tinker]

Lugers were made in batches of 9999 (some experts say 10,000 and that is another thread), so you will find them marked with numbering such as:
1630
or
3 c
123
2578 c
9762 f
etc., so to give you any indication of when your Luger was made, a serial number or close to it needs to be given.

If under the barrel it is marked 5476 and just under it is a y, then the serial number is 5476y. If you feel that giving out the serial number is a violation of your privacy, you can get the number fairly clsoe by staing 54xx y. Without a serial number or as you stated no suffix, then it was made in the grouping later in the year.

3rd Reich Lugers book states: there were numbering of 1937 S/42 of 4500p through 400b, with a total of 126,000 Lugers made that year.

(1936 S/42's continued their number until the p block, and 1937 continued onward).