How to find tractor serial numbers:
TractorData.com lists tractor serial numbers under the individual model. Use the menu at the top to select your tractor manufacturer and model, the serial number list will be on the tractor's data page.
How to read a tractor serial number list:
Tractor serial number lists nearly always show the first tractor built in each year. The other tractors for that year will have successively higher numbers. Your serial number should lie between two of the stated numbers.
The list only shows the number from the first tractor built in each year. Unless you happen to have the first first tractor off the production line, then your particular number will not be on the list. Your number will lie between two listed numbers.
Model years versus calendar years
Tractors, just like automobiles, are manufactured on a model or production year. The new production year usually starts around September. A tractor built in October of 1955 would have been considered a "1956" model. Serial number lists almost always show the production year, not the actual calendar year the tractor was built. This information is generally more useful, because major changes would have been made to a model at the start of the production year, not on January 1.
Read the number carefully
On older tractors, the serial number plate has often faded. Make sure you do not confuse a 7 for a 1. Also, ensure you have read the entire number.
If the plate has faded very badly, try making a rubbing of the imprint. Place a piece of tissue paper over the plate and rub gently with charcoal or a pencil. Another method is to color the number with a marker and then quickly wipe it off, hoping to leave ink in the stamping. Some people have found that they can read the number off the back side of the plate
A serial number is not a tractor's life story
In general, you cannot determine anything but the year from the serial number of an older tractor. You cannot find the exact date of construction, original dealer, or previous owners. Your best chance at finding your tractor's history is to talk to the person you purchased it from. Find out who they bought it from. If you're lucky you may be able to trace it back to the original buyer and the original dealer. If you are really lucky, that dealer would still be around and have records of the sale. There are couple of exceptions...
John Deere owners can contact the Two-Cylinder Club to have their serial number researched for a fee. I am not aware of this service being available for any other brand. If it is, email me and I will post the information.
Newer tractors from major brands will likely be tracked by the factory and its dealer network on computer. If you tractor was built around 1990 or later you may be able to have a dealer run the serial number. The exact information available would depend on the dealer and brand, and what they are willing to release to you. In general, they track sales, repairs, and stolen equipment.
IH owners: look for the U
Many International Harvester tractors will have a long number sequence with the letter "U" in the middle. The numbers on the list correspond to the digits after the letter.
Missing serial numbers
With an older tractor it is not uncommon for a tractor's serial number to be missing. The serial number plate might be lost. The stamping might be worn to the point that it is unreadable. In most cases it is impossible to ever determine the original serial number. The serial number was typically marked in only one location on the tractor. The engine serial number is usually unrelated to the tractor serial number (certain Farmall models are an exception to this).
As Green Magazine's "Mr Thinker" column has stated many times, "If you want a tractor with a serial number plate, you should buy a tractor with a serial number plate".