Automated manual transmissions (AMTs) now dominate new Class 8 truck specs, largely replacing the traditional manual — here's what's actually behind each major OEM's badge, plus where a full automatic still makes sense.
Detroit (Daimler Truck)
Detroit's automated manual transmission, standard behind the DD13/DD15 in the Freightliner Cascadia.
Type
Automated manual (AMT), 12-speed
Pairs with
Detroit DD13, DD15
Available in on-highway and vocational tunings — the on-highway version is what ships in a standard long-haul Cascadia spec.
PACCAR
PACCAR's automated manual, standard behind the MX-13 in both the Peterbilt 579 and Kenworth T680.
Type
Automated manual (AMT), 12-speed
Pairs with
PACCAR MX-13
Like the MX-13 engine it's paired with, the TX-12 is the same transmission across both Peterbilt and Kenworth badging.
Volvo
Volvo's automated manual, the only transmission offered behind the D13 in a VNL.
Type
Automated manual (AMT), 12- or 13-speed
Pairs with
Volvo D13 only
Since Volvo doesn't offer an outside engine or transmission brand in the VNL, the I-Shift is a fixed part of the spec, not a choice.
Eaton Cummins
The modern automated successor to the classic Eaton Fuller manual — sold as a 12-speed (HD) or 18-speed (XD/XD Pro) automated manual, available across multiple OEM chassis rather than tied to one truck brand.
Type
Automated manual (AMT)
Torque rating
Up to 1,850 lb-ft
Overall ratio
18.85:1 (HD 12-speed); 20.5:1 (XD/XD Pro 18-speed)
Oil change interval
Up to 750,000 miles (HD, line-haul duty)
Eaton markets the Endurant as the lightest heavy-duty automated transmission on the market — about 105 lb lighter than comparable competitors, which is real payload capacity, not a marketing rounding error.
International (Navistar)
International's 14-speed automated manual, sold only as part of the S13 Integrated Powertrain.
Type
Automated manual (AMT), 14-speed
Pairs with
International S13 only
Optimized for
Direct drive operation
The extra gears (14 vs. the 12 most competitors use) are aimed at keeping the S13 in its most efficient RPM band across more load and grade conditions.
Allison
A full torque-converter automatic (not an automated manual) — the choice for vocational and severe-duty applications where clutch-based AMTs wear faster, like refuse, construction, and heavy off-road work.
Type
Full automatic (torque converter, not clutch-based)
Horsepower range
380–800 hp (4000 Series)
Torque capacity
Up to 2,360 lb-ft
Gears
6 or 7 forward (4000 Series); 10-speed also available
Allison's torque-converter design is the real differentiator from every other transmission on this list — it's the standard choice when a duty cycle (stop-and-go, off-road, PTO-heavy) would wear out a clutch-based AMT faster than a fleet wants to deal with.
No — an AMT (like the Detroit DT12, PACCAR TX-12, or Eaton Endurant) is mechanically a manual transmission with a computer-controlled clutch and shifter, not a torque converter. Allison's transmissions are true automatics with a torque converter, which is why Allison is the standard choice for stop-and-go or off-road duty cycles that wear out a clutch-based AMT faster.
It's increasingly rare — most major OEMs have shifted their standard (and often only) long-haul spec to an automated manual. If a true manual matters to you, you'll likely need to special-order it or look at the used market.
Volvo engineers the D13 engine and I-Shift transmission together as an integrated powertrain rather than sourcing them separately — the tradeoff for tighter engine-transmission tuning is losing the ability to mix in an outside transmission brand.
Specs reflect common current factory options and can change by model year or region — always confirm exact figures against the manufacturer's current build sheet before making a purchase or maintenance decision.