6.6L Duramax L5D

Silverado 4500, 5500, 6500 Duramax L5D Specs & Information

The Duramax L5D is more-or-less a commercial version of the L5P found in Chevrolet Silverado and GMC Sierra 2500/3500HD models. The L5D made its debut for the 2019 model year, being featured exclusively in the new Silverado 4500, 5500, and 6500 chassis cabs. As a detuned version of the pickup engine, the L5D produces 350 horsepower and 700 lb-ft of torque; it is coupled to one of several Allison transmission options. For 2019, the 6.6L Duramax is the only available engine for the 4500/5500/6500 chassis cabs, although a gas engine option is likely to be added in the future based on industry trends in the commercial vehicle segment.

The commercial L5D is rated at a peak 350 horsepower and 700 lb-ft of torque to the pickup version's (L5P) 445 horsepower and 910 lb-ft of torque. While the L5D does feature subtle differences from the L5P, the most significant deviation is in the engine tuning. Reducing engine output in commercial vehicle applications is a common practice due to the high gross vehicle weight ratings; limiting the peak horsepower and torque output promotes reliability and longevity in addition to maximizing fuel economy. The Silverado 4500/5500/6500 models are available with GVWRs ranging from 15,000 - 16,500 lbs, 17,500 - 19,500 lbs, and 21,500 - 23,500 lbs, respectively.

6.6L Duramax L5D Specs


6.6L Duramax L5D turbodiesel


90° V-8

Assembly Location:

DMAX assembly plant in Moraine, Ohio


2019 Chevrolet Silverado 4500 chassis cab
2019 Chevrolet Silverado 5500 chassis cab
2019 Chevrolet Silverado 6500 chassis cab


403 cubic inches (6.6 liters)

Cylinder Head Material:

Aluminum alloy

Engine Block Material:

Cast iron

Compression Ratio:

To be confirmed

Firing Order:



4.055" (103 mm)


3.897" (99 mm)


Variable geometry turbocharger, air-to-air intercooler


Direct injection, high pressure common rail system


OHV (overhead valve), 4 valves per cylinder (32 valve), mechanical roller lifters

Oil Capacity:

10 qts w/ filter

Fuel Compatibility:

Ultra low sulfur diesel (ULSD) or max B20 biodiesel blend

Governed Engine Speed:

2,900 RPM

Peak Horsepower:

350 hp @ 2,700 RPM

Peak Torque:

700 lb-ft @ 1,600 RPM

Allison Transmission Options

The 6.6L Duramax L5D is available coupled to one of several automatic transmissions from Allison, including 1700, 1750, and 2700 model designations in highway service (HS), rugged duty service (RDS), emergency vehicle service (EVS), and motor home series. All available transmissions feature 6 forward speeds and are applicable to different GVWR ranges; recall that the Silverado 6500 is available with a gross vehicle weight rating of up to 23,500 lbs.

Allison 1700/1750/2700 Transmission Ratios

Transmission Model








1700, 1750, 2700 (HS/RDS/EVS/MH)

3.10 : 1

1.80 : 1

1.40 : 1

1.00 : 1

0.70 : 1

0.61 : 1

4.49 : 1

2019 Chevrolet Silverado 6500

2019 Chevrolet Silverado 6500
Source: chevrolet.com