You're looking at an old red-and-gray Ford with a 600, 800 or 900 emblem on the nose, and someone has told you it's a 640, or an 860, or a 950. Which is it, and does the number mean anything? It does. Ford's 1955–1957 tractors, known as the Hundred Series, carry a three-digit model number that tells you the engine size, the tractor layout, the transmission, the PTO and the lift, plus a separate serial number that dates the tractor.

The trouble is that the hood emblem only shows the series (600, 700, 800 or 900), not the full model. To know exactly what you have, you need the stamped model number, and you need to read it correctly. This page walks through each digit, then decodes real-format numbers step by step.

Where the numbers are stamped

On Hundred Series tractors the model and serial numbers are stamped on the left side of the tractor, on the flat pad above and behind the starter, where the engine meets the transmission housing. The top line is the three-digit model number. The line below it is the serial number, with a diamond symbol at each end (N Tractor Club Quick ID guide; Tractor Data).

The stamping is shallow and often under decades of grease and paint. Clean it with a wire brush and degreaser, then read it with a flashlight held low and to one side so the light catches the edges of the digits. Don't confuse it with the numbers cast into the engine block; those are part numbers, not the tractor's identity (more on that below).

The three digits

First digit: layout and engine

6__Four-wheel utility tractor with adjustable front axle, 134 cu in gas or LP-gas engine
7__High-clearance row-crop tractor, 134 cu in gas or LP-gas engine
8__Four-wheel utility tractor with adjustable front axle, 172 cu in gas or LP-gas engine
9__High-clearance row-crop tractor, 172 cu in gas or LP-gas engine

Second digit: transmission, PTO and lift

_2_4-speed, no PTO and no three-point lift
_3_4-speed with three-point lift, no PTO
_4_4-speed with PTO and three-point lift
_5_5-speed with three-point lift and PTO (not live)
_6_5-speed with three-point lift and live PTO (two-stage clutch)

Third digit: series. A 0 means the original Hundred Series. Ford introduced it in late 1954 as 1955 models and built it through 1957. A 1 means the "01" series that replaced it, introduced in late 1957 for 1958 and sold through 1962: the 601 and 701 Workmasters and the 801 and 901 Powermasters.

These tables follow the N Tractor Club's decoding chart. Not every combination was built. Tractor Data, for example, lists the 740 as the 700 Series model and 820, 840, 850 and 860 for the 800 Series.

Worked examples

Example 1: a stamping that reads 850 over ◇93706◇. This is the real stamping pictured in the N Tractor Club guide.

  1. First digit 8: four-wheel utility, 172 cu in engine.
  2. Second digit 5: five-speed, three-point lift, PTO that is not live.
  3. Third digit 0: original Hundred Series.
  4. Serial 93706 falls between 77,271 and 116,367, the 1956 range.

Result: a 1956 Ford 850.

Example 2 (made-up example): 640 over ◇45210◇.

  1. 6: utility, 134 cu in.
  2. 4: four-speed with PTO and lift.
  3. 0: Hundred Series.
  4. 45210 falls in the 1955 range (10,615 to 77,270).

Result: a 1955 Ford 640, the most basic fully equipped 600.

Example 3 (made-up example): 960 over ◇121880◇.

  1. 9: high-clearance row-crop, 172 cu in.
  2. 6: five-speed with live PTO.
  3. 0: Hundred Series.
  4. 121880 is above 116,368, so it's a 1957.

Result: a 1957 Ford 960.

Example 4 (made-up example): 861 over ◇62400◇.

  1. 8: utility, 172 cu in.
  2. 6: five-speed with live PTO.
  3. 1: this is an 01-series tractor, an 801 Powermaster, not a Hundred Series.
  4. Because it's 01-series, use the 01 serial chart: 62400 falls in the 1959 range (58,312 to 105,942).

Result: a 1959 Ford 861. Read with the Hundred Series chart, the same serial would wrongly say 1955. Always read the third digit before you look up the serial.

Serial number ranges

Hundred Series (third digit 0)1954: 1–10,614. 1955: 10,615–77,270. 1956: 77,271–116,367. 1957: 116,368 and up
01 Series (third digit 1)1957: 1,001–11,996. 1958: 11,997–58,311. 1959: 58,312–105,942. 1960: 105,943–131,426. 1961: 131,427–155,530. 1962: 155,531 and up

Sources: the N Tractor Club Quick ID guide and My Ford Tractors. A tractor with a 1954 serial was built in late 1954 but sold as a 1955 model.

The 01 series uses extra codes

If the third digit is 1, the second digit has three more possible values, because Ford added the Select-O-Speed powershift in 1959: 1 means Select-O-Speed with no PTO, 7 means Select-O-Speed with single-speed PTO and lift, and 8 means Select-O-Speed with dual-speed and ground-speed PTO and lift. A 771, for example, is a 134 cu in row-crop Workmaster with Select-O-Speed. The 01 series also added suffixes after a dash: -1 for a single front wheel, -4 for high clearance with a wide front, -5 for a factory wide front, -L for LP-gas and -D for diesel. The diesel engines (144 cu in in the 600 and 700 sizes, 172 in the 800 and 900) arrived with the 01 series; the Hundred Series was gas or LP only.

Mistakes to avoid

  • Trusting the hood emblem. It shows the series only. A 900 emblem could be on a 940, 950 or 960, and emblems and hoods move between tractors.
  • Treating the badge as proof of the engine. Engines have been swapped for 70 years. The block has a cast part number on the lower right side: EAE 6015 is the 1953–1957 134, EAF 6015 the 1953–1957 172 (per the N Tractor Club guide). A 640 stamping with an EAF block is a 640 with an 800-size engine, and parts orders should follow what's actually in it.
  • Mistaking a casting number for the serial. Block and housing castings carry part numbers and date codes. The tractor's serial is the stamped number between diamonds on the pad behind the starter.
  • Using the wrong serial chart. Hundred Series and 01 Series serials overlap in the numbers they use. The third digit tells you which chart applies.
  • Assuming a 5 or 6 in the second digit means live PTO. Only a 6 has the two-stage clutch. A 650 or 850 has a five-speed with a transmission-driven PTO that stops when you clutch.

The individual series

Once you've decoded the number, go to the series page for what to check on that tractor: