Kenworth T680 replacement engines & transmissions
Kenworth T680 Engines & Transmissions
The T680 has been built since 2012, with a Next Generation version launched in 2021, with PACCAR and Cummins engines and several automated and manual transmissions along the way. Send us your VIN and unit details and we search supplier sources for a matching used replacement.
Engine families
Engines to check
Transmission families
Transmissions to check
All Kenworth trucks
Factory options varied by model and year. Links are starting points, not a fitment guarantee — we confirm against your VIN and serial numbers.
01Original T680 and the 2021 Next Generation
Kenworth unveiled the T680 at the Mid-America Trucking Show in March 2012, built at its Chillicothe, Ohio plant and offered at launch as a day cab or with a 76-inch sleeper. In February 2021 Kenworth launched the T680 Next Generation, offered as a day cab and with 40-inch, 52-inch and 76-inch sleepers.
Kenworth said the original and Next Generation versions could be ordered side by side through at least the end of 2021, so a truck's build year alone does not tell you which version it is. The VIN and build data settle it, and that matters because cab, electrical and powertrain integration changed between them.
02Engines offered in the T680
At launch, the 12.9-liter PACCAR MX engine (the MX-13) was standard and the Cummins ISX15 was optional. The Next Generation T680 launched with the EPA 2021 PACCAR MX-13 as standard. The PACCAR MX-11 has also been offered, and Kenworth began taking orders for the MX-11 paired with the PACCAR automated transmission in 2018.
Cummins diesel engines have continued alongside PACCAR power: Eaton announced the Endurant HD paired with the Cummins X15 for the T680 in 2020. Natural gas versions have also been built, including the Cummins Westport ISX12N (2021) and the Cummins X15N, which Kenworth scheduled for T680 production from the third quarter of 2024.
03Transmissions offered in the T680
PACCAR's 12-speed automated transmission, developed with Eaton and now known as the TX-12, became the standard spec for the T680 Advantage when orders opened in October 2017. The Eaton Cummins Endurant 12-speed automated manual was also offered from 2017, and the PACCAR TX-18 was added for MX-11 and MX-13 equipped T680 Next Generation trucks in 2022.
Automated transmissions on a T680 are tied to the engine and truck electronics, so we match by the transmission label and VIN rather than by speed count alone. If your T680 has a manual transmission, send the tag details from the transmission case.
04Matching an MX-13 or X15 to your T680
An MX-13 from a 2013 T680 and one from a 2022 Next Generation T680 are different emissions generations, and they can differ in sensors, harness, ECM software and aftertreatment. The same applies to a Cummins ISX15 versus an X15. Kenworth has also offered a low-NOx MX-13 certified for California since 2024. Give us the engine serial number so we search for the right generation.
Trucks that switch engine families, such as MX-13 to X15, are conversions involving mounts, cooling, wiring and the transmission controls. Most owners replace like for like, and that is what we search for unless you tell us otherwise.
05What to have ready
To start a T680 search, have:
- Full VIN (tells us original vs Next Generation)
- Engine model and serial number (PACCAR or Cummins)
- Transmission label: TX-12, TX-18, Endurant or Eaton Fuller model and serial
- Sleeper or day cab, and approximate mileage of the failed unit
- Whether you need a complete engine, long block or transmission only
FAQ
Kenworth T680 engine & transmission questions
How do I know if my T680 is a Next Generation truck?
Kenworth launched the Next Generation in February 2021 but kept taking orders for the original version through at least the end of that year. Check the build data tied to your VIN rather than going by the model year.
Which engine came in my Kenworth T680?
Many have a PACCAR MX-13, but MX-11, Cummins ISX15 and Cummins X15 engines were also offered, plus natural gas options. The engine dataplate or the build data tied to your VIN tells you which.
Can I replace a TX-12 with an Endurant or a manual?
That is a conversion that involves controls, wiring and software. Most T680 owners replace an automated transmission with the same model, and we search by the label on your unit.
Will an MX-13 out of a Peterbilt 579 work in my T680?
Both trucks are PACCAR products and use MX-13 engines, but emissions year, ECM software and installation details still have to match. We compare engine serial numbers and your VIN before quoting.
Are you a Kenworth dealer?
No. We are an independent sourcing company. We search supplier sources nationwide and confirm availability and freight on your quote.
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Ready when you are
Replacing the engine or transmission in your Kenworth T680? Start with the VIN.
Have your engine serial number, CPL and VIN handy. If you don't, we'll help you find them.
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