I’m going to give my one-cent worth of information here again, and again let’s keep it simple.
The 1st deuce as we all know and love is the CCKW – GMC. I’m going to go out on the limb here and say that it was referred to as the Jimmy, CCKW -503 or 353 and so forth, I have never seen anywhere (not saying there isn’t) to where these true WWII deuces had an identification starting with an “M”. They were 6-volt systems and I wouldn’t be surprised if they first came out with a positive ground. In WWII we did not have the time or recourses to develop vehicles that had interchangeable parts from different type vehicles, if there was, it was purely by accident, or there was no other part like it, so everybody used it.
After WWII the military started to standardize nomenclatures for the ease of inventory. Naturally when the military wanted to standardize military vehicles and wanted a replacement for the CCKW, they started with the M211, M135, M35, and so forth. If you look closely at these vehicles, you will find they are all 24 volt systems, (they all use the same light bulbs, gauges, wire connection, light assy, and the list goes on.) as in WWII, half track gauges will not fit CCKW so and so forth, so a blind man can see that inventory and supply was a night mare. Even today you can get a fuel gauge built to for today’s trucks that will fit in the M211’, M135’s, and the M35’s THE EARLY "M" SERIES TRUCKs. I don't think the pharse "The early duece" refers to just one model, and if it does it's just someone's own perference. If you look into on how the "M" series trucks started you have to group the three together, first three that were going throught the test period at the time. I’m figuring the dividing line from early deuces to the late models is when the multifuel engines came into play. Again common sense and keeping it simple, especially when your dealing with the military goes along way. I spent 20 years in the Air Force as a mechanic/Crew Chief on an AC-130 Gunship, you learn very early to keep it simple and easy.
Steve