One thing I found odd, the stock is not numbered internally. I could not find any evidence of a number ever existing. The stock is numbered externally and matching Butt plate as well.
see photos beginning in post #3
Well, it took some time, but I reviewed 1909-1917 DWM stock trends so far as they exist, - the combination of scarcity of factory stocks, the irregularity in disassembly, coupled with the fact most do not take pictures where markings do not exist all make this a tricky question to determine.
It "seems" that pre-1910 they did serial the stock internally, or the few I viewed seem to make this probable.. However when DWM took up G98 production in 1914 they seemed to have neglected to reintroduce this practice, this clearly was carried on for some time, but there are nearly a dozen that show the handguard serial but avoid the internal stock, often showing BC's and bolt lower flats, so I assume in these cases there was an absence of internal serialing based upon the fact that every 1915 DWM from 1915 either shows this practice or clearly the serial is not present (6 rifles clearly show a lack of serial, a further 8, including my 3167/w show the handguard but not the stock serial and I certainly recorded everything else and it is unimaginable I overlooked a serial if it existed... but this was 2004 before I was trending such things, Cyrus too had a couple that I believe were like this, but some may have been 1916's)
1916, this continues in 1916 and at least 9 show this lack of a serial internally, perhaps half a dozen others show HG but not the stock serial location.
1917 serialing began showing serials internally to the stock, but I misplaced the sheet where I wrote the statists down, I did note that one DWM/16 s-block in Imperial trim, but EWB marked, is the earliest internal serial, whether this is supported by others later, and so far it is not, many rifles in the 16-double suffix clear do not have the serialing, this is probably some postwar modification... though the stock is DWM/16 and the RS is Imperial.
Anyway, I wanted to get this posted today, tomorrow I will seek out my notes on 1917 where if my recollection is correct it does start internal serialing.