The 600 Series is the most common of Ford's Hundred Series tractors, the line Ford introduced in late 1954 as 1955 models to replace the NAA. If you've found a gray-and-red Ford utility tractor with a 600 emblem on the nose, you probably have one. The question is which one, because a 620 and a 660 look almost the same from the road and are very different tractors to use.

This page covers how to pin down the exact model, how to tell a 600 from the NAA, the 800 and the later 601 Workmaster, how to date it, and what to check before you buy it or try to get it running.

What a 600 is

The 600 is a four-wheel utility tractor with an adjustable front axle and Ford's 134 cu in overhead-valve four-cylinder, gasoline or LP-gas. The N Tractor Club describes it as "basically the 134 cubic inch NAA with a few updates": an improved hydraulic lift, and one-piece rear axles in place of the NAA's separate axle and hub (Quick ID guide). The real change was the options. Depending on the model, you could get a five-speed instead of a four-speed, and a live PTO through a two-stage clutch.

Which 600 do you have?

The exact model is the three-digit number stamped on the left side of the tractor, on the flat pad above and behind the starter. The top line is the model, the line below is the serial between two diamond symbols. The middle digit is the one that matters within the 600 Series:

6204-speed, no PTO, no three-point lift
6304-speed with three-point lift, no PTO
6404-speed with PTO and three-point lift, the most common
6505-speed with three-point lift and PTO (not live)
6605-speed with three-point lift and live PTO

For how each digit works across all four series, see Decoding Ford Hundred Series Model Numbers. You can confirm what the stamping says by looking at the tractor itself. A four-speed and a five-speed have different shift patterns, and a 620 has no lift arms, no PTO stub and no lift linkage at all.

Telling it from look-alikes

From an NAA (1953–1954). Look at the rear wheel hubs. The NAA's rear hub is held on by a large nut in the center; 1955 and later tractors have one-piece axles with no center nut. The NAA's serial also starts with the letters NAA, while a 600's serial is numbers only, with the model number stamped above it. The hood emblem helps too: the Hundred Series emblem shows the series number, while NAA emblems read Golden Jubilee (1953) or have a ring of stars (1954).

From an 800. The two share sheet metal and look almost identical. Per the N Tractor Club, the 800's hood sits about 2 inches higher to fit a bigger fuel tank (Tractor Data lists 11 gallons for the 640 and 14 for the 860), and its rear differential housing is larger. The surest check is the number cast into the lower right side of the engine block: EAE 6015 is the 1953–1957 134, EAF 6015 is the 172.

From a 700. The 700 is the high-clearance row-crop version with the same engine. Tractor Data lists a 75.2-inch wheelbase for the 640 against 85.3 inches for the 740, and the N Tractor Club describes the 700 as a tricycle, with a wide front as an option.

From a 601 Workmaster (1958–1962). The 01-series Workmaster has a third digit of 1 (641, 661 and so on), an all-red hood with gray only on the grille, fenders and wheels, a plastic hood emblem, and restyled rear fenders.

Reading and dating the serial

The serial is on the same pad, below the model number. Hundred Series ranges: 1954, 1–10,614; 1955, 10,615–77,270; 1956, 77,271–116,367; 1957, 116,368 and up (N Tractor Club; Tractor Data gives the same starting numbers).

Worked example (made-up numbers): 660 over ◇101350◇. The 6 in the middle means a five-speed with live PTO. The serial falls between 77,271 and 116,367, so it's a 1956 Ford 660. A tractor with a serial under 10,615 was built in late 1954 but sold as a 1955 model.

Specifications

EngineFord 134 cu in 4-cylinder overhead-valve, gasoline or LP-gas
Power31 belt hp tested (640); 34 belt hp tested (660), per Tractor Data
Transmission4-speed or 5-speed unsynchronized, depending on model
HydraulicsOpen-center, three-point hitch with position and draft control, 1,250 lb lift (none on the 620)
Electrical6-volt, positive ground, generator
Wheelbase / weight75.2 in / about 3,030 lb unballasted (640)
BuiltLate 1954 through 1957 (1955–1957 model years)

Figures from Tractor Data.

What to check before buying or reviving one

  • The stamping and the block. Read the model number and serial, then find the casting number on the block. A 640 stamping over an EAF block means someone has fitted an 800 engine. That's not a dealbreaker, but parts need to match the engine actually in it.
  • The two-stage clutch on a 660. With the engine running and the PTO engaged, push the clutch halfway: the tractor should stop moving while the PTO keeps turning. Push it all the way and the PTO should stop. If the PTO stops at the halfway point, the clutch needs adjustment or work.
  • The lift. Raise a heavy implement and leave it up for several minutes with the engine off. It should not drift down noticeably. Then check draft control works by watching the hitch respond as an implement pulls harder.
  • Oil condition. Check the engine oil for coolant (milky or tan), and drain a little from the bottom of the transmission and rear end to look for water, especially on a tractor stored outside.
  • Electrics. These came as 6-volt, positive ground. Many have been converted to 12 volts. Find out which yours is before you buy a battery, a light or a maintainer; the battery maintainer guide covers choosing a 6-volt one.
  • Front end and steering. Rock the front wheels and watch the spindles and steering for play, especially on a tractor that has carried a loader.

Mistakes to avoid

  • Buying a 620 or 630 for PTO work. Neither has a PTO, and the 620 has no three-point lift either. Adding them is not a bolt-on afternoon job. Check the stamping, not the seller's description.
  • Ordering parts by the emblem. The emblem only says 600. Clutch, transmission and PTO parts differ between four-speed and five-speed models, and engine parts differ if the block has been swapped.
  • Expecting a 650 to have live PTO. It has the five-speed but a transmission-driven PTO, so a mower or baler stops whenever you clutch. Only the 660 has the two-stage clutch.
  • Hooking up a 12-volt battery without checking the system. On an unconverted 6-volt, positive-ground tractor, that can burn out the starter, the generator and the gauges.
  • Taking a big loader at face value. A 600 is a light tractor. If you need serious loader work, an 800 Series with the 172 engine and heavier rear end is the better match.