Early production models (like "Prefix" or serial number 501) and final-year models often hold higher collector value. How to Locate and Read IH Serial Numbers
International Harvester cast a specific date code into almost every major iron casting (engine block, transmission housing, torque tube). These codes consist of digits followed by a letter. Month · Day · Year Code Example: 4 · 12 · P translates to April 12, 1946. IH Year Casting Letters: I: 1939 J: 1940 K: 1941 L: 1942 M: 1943 N: 1944 O: 1945 P: 1946 Q: 1947 R: 1948 S: 1949 T: 1950 W: 1951 X: 1952 Y: 1953 Z: 1954
Styling changes often happened mid-year. Knowing the precise year ensures you buy the correct matching components.
Look on the left side of the clutch housing (torque tube) just ahead of the brake pedals. International Harvester Tractor Serial Number Table-
International Harvester serial numbers do more than just identify a tractor; they serve as the machine's birth certificate. Dating IH tractors is distinct from modern vehicles because IH used a , not model-year designations. The official tractor data is typically presented in a table that lists the first serial number produced at the beginning of each calendar year. By comparing a serial number to the numbers in the table, you can pinpoint the tractor's year of manufacture.
Many antique IH tractors lose value because the serial tag rots away. These tags were originally aluminum (post-1950) or tin (pre-1950). To preserve yours:
Below are the most sought-after tables. Note that serial numbers began at 501 for most early models (excluding prototypes). Early production models (like "Prefix" or serial number
The cycle repeated with new letter styles and formats for the late 1950s, 1960s, and 1970s models. Example Decoded
Typically located on the right or left side of the transmission housing, near the operator's platform. Reading the Suffix Codes
The tractor that started the row-crop revolution. The Regular was the first mass-produced tractor with a clear view of the row ahead. Serial numbers began at in 1926 and ended near The Letter Series (1939–1954) The iconic A, B, H, and M series changed farming forever. Introduced in 1939 with serial number , production ran through 1953, reaching over Month · Day · Year Code Example: 4
Typically found on a metal tag on the left or right side of the seat support.
International Harvester stamped a unique serial number into the engine block itself. While the engine type matched the tractor model, the numbers rarely matched the chassis serial number.
International Harvester Tractor Serial Number Table: The Ultimate Guide
To find the year:
I can provide target dates and specific factory feature variations for your machine. Share public link
