No model suffix letter on my wartime 102s, do I assume they are “C” or “D”?

[EdgarFB]

I have a 1940 hmv 102 (date code B4) and a 1939 (code B3) both just have “102” as the model type, not as I’d expect 102c or possibly 102d… did they ditch the letter suffix during the war?

[Inigo]

My B/9 from 1945, MOS unit, is a 102 D

[EdgarFB]

My B/9 from 1945, MOS unit, is a 102 D
IMG20240617182944.jpg

Yes I have a 1945 MOS also stamped with a D. But absolutely no letter stamped on either of my war time civilian 102s. Just "102"

[Inigo]

The D in mine seems to be a later addition, using an earlier ivorine plate, so maybe they were using id plates from remaining stock, maybe it was because of the war, or because these were for MOS. Clearly there were earlier ivorines with the letters C or D properly stamped. As I've seen all these in a fast Google search:

[EdgarFB]

The D in mine seems to be a later addition, using an earlier ivorine plate, so maybe they were using id plates from remaining stock, maybe it was because of the war, or because these were for MOS. Clearly there were earlier ivorines with the letters C or D properly stamped. As I've seen all these in a fast Google search:

Interesting that the 1939 you found there also doesn't have a letter. So what physical characteristics actually make a machine a model "C" or "D"? .... I'm wondering if during the early war years they weren't able to consistently manufacture the machines to C or D spec due to recycling older parts from earlier iterations, so they just labeled them without the revision letter. Could be early wartime machines weren't technically Cs so weren't labelled as such?

Is there a good resource on what updates to the design actually made the difference between a B, C and D?