A Farmall A with a serial between 281569 and 300125 was made in 1950. Source: http://www.geocities.com/mck357/serialnumbers.html
You can check at TractorData.com or link below
You have to compare the serial number to a chart that shows what year it was made.
Check at TractorData.com or link below
The Farmall M started being produced in 1939 and continued until 1952 producing 290,000 units. They sold for $1100.00 in 1940
A Farmall M tractor weighs just over 5000 lbs.
Farmall M is a tractor and is row crop version of McCormick-Deering W-6. In 1960 the production was ceased at Farmall and then it continued at Doncaster.
There are several websites with great information on restoring a Farmall M. One of these websites is farmalltractors.org.
You should be able to get ahold of Farmall and they should have records. Although I am not for sure.
any number in series over 25000 is after 1945 and is also a Super A. you should search your year make and model at yesterday'stractor.com.
The last tractor branded as a Farmall was in 1975.
On the metal tag on the side of the bell housing.