Free serial number decoder
Type the serial number. Get the year — with the starting-serial bracket it fell in, the sources behind the table, and the traps that make old tractors read wrong: swapped engines, casting dates that are not serial numbers, and the John Deere lists that disagree by a year.
Pick the brand, pick the model, type the number exactly as stamped. The answer shows the bracket your number fell in and the sources behind it.
21 models at launch: Ford N-series & NAA · Farmall H, M, C, A/B and the Supers · John Deere A, B, H, M and 50 · Massey Ferguson 135 (both factories), MF 35 and the Ferguson TO series. Nothing you type leaves your browser.
Why this exists
Find a scanned table on a parts site. Find your model page on a 1999 reference site. Squint at a column of starting numbers and work out which two your number sits between — then discover a second site that gives a different year and no explanation.
Serial in, answer out — the same tables, cross-checked against a second published source before they were allowed in. Where sources disagree, the result says so and shows both calendars. Where a factory split the series, the decoder asks about the factory first.
Four brands
9N, 2N, 8N and the NAA Golden Jubilee. Hand-stamped engine numbers, star and diamond marks, and the famous trick: the 2N wears a 9N prefix.
H, Super H, M, Super M, C, Super C and A/B. Prefix codes decoded, option suffixes explained, and the IH casting-date letter code as a built-in second check.
A, B, H, M and the 50 — read on the production-year calendar from Deere's own Serial Number Registers, with the fiscal-year disagreement disclosed on every result it affects.
The 135 asked the factory question first — Detroit and Coventry used different numbers for the same tractor. Plus the UK MF 35 and the Detroit Ferguson TO-20, TO-30 and TO-35.
The honesty rule
A John Deere A with serial 577582 is a 1947 on the production-year list and a 1946 on the older fiscal-year list still copied around the internet — a list that also contains a misprinted number (588817) that copyists later "fixed" to a second wrong number. Most sites pick one list and stay silent. Our Deere results use the production-year list and disclose the fiscal-year answer wherever the two part company.
Start from the tractor, not the number
Half the battle is knowing what you have. Answer a few questions about gears, size and levers and we will point you at the right decoder.
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
Straight answers
No — and confusing them is the most common dating mistake there is. A casting date says when that lump of iron was poured. Ford castings then sat at least 30 days before machining, and the serial was stamped only after the engine passed inspection. A casting date weeks or months older than the serial's year is normal; a casting date NEWER than the serial's year means that part was replaced later.
Because Deere published two lists. The first used its fiscal year; the corrected list uses production (model) year and comes from Deere's Serial Number Registers. For a band of 1940s serials the two lists land a year apart. We use the production-year list and disclose the difference on the result. The full story.
Often, yes — approximately. Farmall owners can read IH casting date codes on the major castings (we have a decoder guide for the letter codes). Ford owners can read block casting codes the same way. What you cannot do is recover the exact serial-year bracket without a number; casting dates give you a window, not a verdict.
By itself, a little. What moves money is what the year unlocks: first-year and last-year tractors, mid-run breaks (the 8N's distributor move, the Deere A frame change at serial 584000), originality, and options. The Buyer's Check Kit prices those factors family by family.