Serial location guide
Farmall put the tractor's identity on an aluminum plate — good news for readability, bad news because plates pry off, corrode, and get swapped with seats and housings. Here is where to look, model by model.
The plate is riveted to the left side of the clutch (bell) housing. The prefix names the model: FBH = H, SH = Super H, FBK = M. On a Super M the first letter is the plant — F for the Farmall Works, L for Louisville — and the two plants ran different number series, so the letter decides the table.
Backup: the same serial is stamped on a flat pad on the engine block (on the H, near the No. 1 spark plug / above the distributor). Chassis and engine numbers matched when new; if yours differ, the engine has been changed at some point in 70 years — date the tractor by the plate.
The plate sits on the seat support (toolbox), prefix FC for both models. The number itself splits them: five digits (up to 80432) is a C; six digits (100001 up) is a Super C. Because the plate rides on the seat support, a swapped seat can carry the wrong identity — cross-check with casting dates.
Plate on the left side of the seat support. A and B share one number series, so the plate gives the year; which model it is comes from the tractor itself (offset driver's platform = A, centered = B).
Suffixes like X1 are factory option codes, not part of the serial: X1 = gasoline, X3 = kerosene, X17 = distillate, with further codes for gearing and altitude pistons. A lone J commonly marks a Rockford clutch. Decode the digits for the year; keep the suffix as equipment evidence.
The decoder gives you the year. The kit gives you the rest of the check before money changes hands: serial-verification worksheets, the two-numbers check that catches swapped engines, year-split parts traps, and an inspection checklist for each family.
Included in the $39 Buyer's Check Kit