HOW ABOUT THAT MM Z QUESTION?

I'll assume you are referring to the ZT tractors rather than the later ZA and ZB. Skipping past the "37 in '36" production started in 1937 with the ZTU and ZTN and the ZTS which had it's own serial number range. Production went till 1947 on the ZTS and to 1948 on the others, which by 1947 included the ZTE. There were a handfull of industrials made in the early years. Tested at Nebraska the Z made 25.2 h.p. at the belt on distillate and 30.55 on gasoline. The tractors weighed about 3700 lbs., varying with type and equipement. They could be had on steel or rubber, and never had a foot clutch or live power. The older tractors are a little more popular because they look neater with the cast front and rear wheels with demountable rims as opposed to the later stamped steel wheels. The early tractors had the full flat top fenders which changed to the full crown in 1938 I believe and then the later tractors changed to the clam shell in 1945. The early tractors also had the air intake on the left side of the hood and looked neater too as they had a taller stack. In 1940 the air cleaner and short stack were moved to the right side of hood. Curt gave you a good overview of the ZT vs. later ZA's and ZB's, but the ZT's were always known as such, albeit people just referred to them as Z's. Hope this helps.

Jim