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Which Cummins do I have?

Three checks, in order of reliability: model year, VIN decode, and what you can see under the hood. Two model years (1998 and 2007) had two different engines, so the year alone isn't always enough. Truck, bus or RV? Jump to the dataplate.

01By model year

Model yearTruckEngine
1989–1993Dodge D/W250, D/W3505.9 12-valve, Bosch VE pump[1,8]
1994-early 1998Ram 2500/35005.9 12-valve, Bosch P7100[2,8]
1998.5–2002Ram 2500/35005.9 24-valve ISB, Bosch VP44[3,9]
2003-early 2007Ram 2500/35005.9 common-rail, Bosch CP3[4,10]
2007.5–2026Ram 2500/35006.7[5,6,11]

Split years. The 24-valve ISB replaced the 12-valve partway through the 1998 model year, the start of what's called the "1998.5" trucks.[3] The 6.7 replaced the 5.9 common-rail partway through 2007, the "2007.5" trucks.[5] Within the common-rail years, a mid-2004 change also matters: engines built from January 1, 2004 ("2004.5") got new injectors and turbo.[4] For a split-year truck, the build date on the door-jamb label plus a VIN decode settles it.

02By VIN

The VIN encodes the engine. On Dodge and Ram trucks it's commonly read from the 8th character, but the same letters were reused across eras, so don't guess from a chart. Decode the full VIN instead.

  1. Copy the 17-character VIN from the windshield plate, door-jamb label or title.
  2. Paste it into NHTSA's free vPIC VIN decoder.[7] Look at the engine fields (displacement, fuel type, and engine model or manufacturer where reported).
  3. Check that it agrees with the model year table above. If it doesn't, ask a dealer to run the VIN for the original build sheet.

We deliberately don't publish a letter-by-letter VIN engine-code chart. We couldn't verify one across two independent sources for every year.

03Under the hood

12-valve

  • Six separate valve covers, one per cylinder.[3]
  • Mechanical injection: 1989-1993 have the compact rotary VE pump; 1994-1998 have the much larger inline P7100, which needed a wider front timing cover.[1,2]
  • Mechanical lift pump driven by the engine (no electric pump on the block).[3]

24-valve (VP44)

  • One-piece valve cover: red/silver aluminum early, black/silver magnesium from 2000.[3]
  • Electric lift pump on the driver side of the block.[3]
  • Rotary VP44 pump. No fuel rail, and injector lines run straight from the pump.[3,12]

5.9 common-rail

  • A fuel rail feeding the injectors through high-pressure lines, fed by the CP3 pump.[4]
  • Electrically fired injectors, with wiring passing through a rocker box under the valve cover.[4]
  • No EGR plumbing on the engine.[4]

6.7

  • EGR valve and cooler plumbing, and a variable-geometry turbo.[5]
  • Diesel particulate filter in the exhaust; from 2013, a DEF tank and filler for SCR.[5,6]
  • 2025-on trucks use glow plugs instead of an intake grid heater.[13,6]

04Not a Ram? Read the engine dataplate

In trucks, buses and motorhomes the same model can be built with different engines, so the vehicle's year and make don't settle it. The Cummins engine dataplate does: it gives the engine model and the engine serial number (ESN), which is generally 8 digits. Cummins' operation and maintenance manual for each engine shows where the plate sits in its "Engine Identification" section.[14]

  1. Find the dataplate and note the engine model (for example ISB6.7, L9, X15) and the ESN.
  2. Match the model to a family page: ISV5.0, R2.8 / ISF2.8, ISB / B6.7, ISC / ISL / L9 or ISM / ISX / X15 / X12.
  3. Use the ESN with a Cummins-authorized service location for the exact build, and for engine (equipment) recalls. See how those differ from vehicle recalls.

SRCSources

Accessed October 2026. Numbers in brackets throughout the page point here. Brand names are used descriptively.

  1. DrivingLine Cummins History, Lesson 1: '89-'93 5.9L
  2. DrivingLine Cummins History, Lesson 2: '94-'98 5.9L
  3. DrivingLine Cummins History, Lesson 3: '98.5-'02 5.9L
  4. DrivingLine Cummins History, Lesson 4: '03-'07 5.9L
  5. DrivingLine Cummins History, Lesson 5: '07.5-'18 6.7L
  6. Diesel Hub 6.7 Cummins Turbodiesel Specs & Info
  7. NHTSA vPIC VIN Decoder
  8. Diesel Hub 5.9 Cummins 6BT Engine Info (12 Valve)
  9. Diesel Hub 5.9 Cummins ISB Engine Info (24 Valve)
  10. Green Handle Media 2003-2007 5.9L Cummins
  11. Stellantis North America Media What's New for 2026: Ram Heavy Duty
  12. Green Handle Media 1998.5-2002 5.9L Cummins
  13. Cummins Inc. Cummins Launches Next Generation 6.7L Turbo Diesel Pickup Engine System for 2025 Ram Heavy Duty Trucks (press release, Jan 7 2025)
  14. Cummins Inc. (QuickServe) Finding your engine serial number (ESN)