From across a field, the TW-10, TW-20 and TW-30 look like the same big blue tractor. All three share the same frame, the same 401 cu in Ford six and the same cab options, and many have been repainted and re-decaled over 40-plus years. But they made very different power, and the asking prices and parts differ with them. If you're looking at one, or you just bought one with a faded decal, you want to know which you have before you pay for it or order parts.

This page covers how to tell them apart by what's bolted to the engine, where the serial number is and how to date it, and what to check before buying.

Where the TWs came from

Ford introduced the TW series in 1979 to replace its 8700 and 9700, its biggest two-wheel-drive tractors. All three were offered with two-wheel drive or front-wheel assist and an optional Ford cab (Farm Show, 1979). In 1983 they were updated to become the TW-15, TW-25 and TW-35, and in 1990 the TWs gave way to the Ford New Holland 8030 series, which included the 8630.

The three models

TW-10TW-20TW-30
EngineFord 6.6 L 6-cyl dieselFord 6.6 L 6-cyl dieselFord 6.6 L 6-cyl diesel
AspirationNaturally aspiratedTurbochargedTurbocharged and intercooled
PTO hp (tested)About 110About 136About 163
Transmission8- or 16-speed8- or 16-speed16-speed
WeightAbout 11,250–12,900 lbAbout 12,250–12,850 lbAbout 14,600 lb
Price (new)About $36,000About $40,600About $52,300

Figures are from Tractor Data's TW-10, TW-20 and TW-30 pages. All three use the 401 cu in (6.6 liter) six. The 16-speed is Ford's Dual Power: an 8-speed gearbox with a powershifted low range you can switch in and out on the move when the load increases. It was standard on the TW-30 and optional on the other two, which came standard with the 8-speed.

How to tell them apart

Decals fade and get replaced, so go by the hardware:

  • TW-10: no turbo. The intake runs from the air cleaner straight to the intake manifold. If there's no turbocharger on the engine, it's a TW-10 (or a TW-20 or TW-30 that's had its turbo removed).
  • TW-20: turbo, no intercooler. There's a turbocharger on the engine, and the compressed air goes straight to the intake manifold.
  • TW-30: turbo plus intercooler. The TW-30 added an air-to-air intercooler between the turbo and the intake manifold, cooled by a small tip-turbine fan driven by air from the turbo. Farm Show called it the only one of its kind in the industry in 1979, and it was the subject of a 1979 SAE technical paper. If you see that extra plumbing and heat exchanger, it's a TW-30. The TW-30 also had an extra fuel tank (Agriland).
  • Transmission. An 8-speed without Dual Power rules out a factory TW-30.

Then confirm with the decal and the serial date. A TW-35 or TW-25 can look much the same, but TW-15/25/35 serials are 1983 or later.

Finding and dating the serial number

Tractor Data gives the serial number location as under the right grille panel on all three models. Open or remove the right-side panel at the front of the hood and look for the stamped number. Clean it with a wire brush if it's rusty.

The serial numbers are one sequence shared across Ford's models, so a number dates the tractor but doesn't tell you which TW it is. Tractor Data's starting numbers are:

  • 1979: C592200
  • 1980: C635700
  • 1981: C660700
  • 1982: C682200
  • 1983: C694500

Worked example (made-up number): a serial of C665000 falls between the 1981 start (C660700) and the 1982 start (C682200), so the tractor was built in 1981. If that tractor has a turbo and an intercooler, it's a 1981 TW-30. If the seller is calling it a 1979, the number says otherwise, which is worth asking about.

What to check before buying

These tractors are 40-plus years old, and many have very high hours.

  • Cold start and blow-by. Start it cold if you can, and watch for heavy smoke that doesn't clear. With it warm, pull the oil filler cap or breather and look for steady blow-by. Check the oil for coolant (milky, tan) and the coolant for oil.
  • Turbo (TW-20 and TW-30). Look for oil around the turbo and in the intake, and check the shaft for play with the engine off.
  • Intercooler (TW-30). Check that the tip-turbine fan turns freely and the heat exchanger isn't plugged with chaff or leaking.
  • Dual Power. Engage it under load in several gears. It should pick up the lower range without slipping or a long delay.
  • Hydraulics. Run the remotes and the hitch together with an implement attached. Slow lift with remotes working points to a tired pump.
  • Front-wheel assist. On FWA tractors, listen for noise from the front axle on a turn, look for leaks at the hub seals, and check for play in the steering joints.
  • Cab. Check the heat, air conditioning, door seals, glass and wiring. Cab repairs on tractors this age can cost more than you expect.

Mistakes to avoid

  • Trusting the decal. A TW-10 with TW-30 decals is still a 110 hp tractor. Check for the turbo and intercooler.
  • Using the serial number to identify the model. The numbers are shared across Ford's line. Use them to date the tractor, and use the hardware to identify it.
  • Ordering engine parts by model name only. The TW-10, TW-20 and TW-30 share a block but not the induction, and turbo and intercooler parts are model-specific. Give your parts counter the serial number.
  • Skipping the load test. Dual Power and hydraulic problems often don't show up at idle. Drive it with an implement or a load before you agree on a price.
  • Overlooking the cab. A rough cab is easy to dismiss at an auction and expensive to fix later.

If the tractor will sit between seasons, a maintainer keeps the batteries ready; see battery tenders for tractors.