Work Truck Logo
MenuMENU
SearchSEARCH

Mack Trucks Adds 23,000-Pound Rear Axle and 325 Horsepower Engine Rating for Mack MD Series

Mack Trucks now offers a 23,000-pound rear axle and Cummins B6.7 engine with up to 325 horsepower on its Mack MD Series models. The heavier axle and suspension offer increased capability for hauling loads.

Gray chassis cab Mack truck parked.

Mack Trucks now offers the new Cummins B6.7 engine and a heavier axle and suspension for its Mack MD.

Photo: Mack Trucks

3 min to read


In an effort to give Mack Trucks’ vocational customers improved durability and broader options for their applications, Mack now offers a 23,000-pound rear axle and Cummins B6.7 engine with up to 325 horsepower on its Mack MD Series medium-duty truck models.

Designed for a Gross Axle Weight Rating (GAWR) of up to 23,000 pounds, the heavier axle and suspension offer increased capability for hauling loads requiring the most durable trucks. The Mack MD with the 23,000-pound rear axle specifically benefits refuse packers with 11-yard up to 20-yard rear loaders and those Mack MD models being utilized as water trucks holding 2,000 to 2,500 gallons of water. 

Ad Loading...

When paired with the 325-horsepower engine rating and the Allison 3000RDS transmission, the Mack MD is now capable of increased towing capacity if the customer has a trailer.

“The 23,000-pound rear axle expands the applications in the vocational market – with refuse and construction reaping the most benefits,” said Tim Wrinkle, Mack vice president of vocational and medium duty. “The 325 horsepower also offers carriers traversing longer routes or in a hilly or mountainous region a more durable and reliable powertrain. The rear axles on those truck models equipped with a dump body, hook lift or roll-offs take some abuse during the truck’s lifespan. The heavier axle rating has better durability, and the larger horsepower engine will provide enhanced performance.”

The Mack MD6, a Class 6 medium-duty truck model, has a Gross Vehicle Weight Rating (GVWR) of 25,995 pounds, and the MD7, a Class 7 medium-duty truck model, has a GVWR of 33,000 pounds. Both models are exempt from the 12% Federal Excise Tax (FET).

The Mack MD Series models meet the needs of trucking applications requiring dry van/refrigerated, stake/flatbed, dump, and tank truck vocations. The MD6 model does not require a commercial driver’s license (CDL) to operate for non-hazardous payloads. 

The Mack MD Series is an all-new model range built specifically for medium-duty applications. Available in 4x2 configurations, the MD6 and MD7 models feature a sharp wheel cut for enhanced maneuverability for tough urban settings. 

Ad Loading...

Updated Cab for the Mack MD

The MD Series cab was updated in January to a larger cab with a bumper-to-back-of-cab measurement of 107 inches, providing industry-leading comfort. Mack matched the bold look and styling of the Mack Anthem, Mack’s highway model, as a basis for the grille and hood design found on the MD Series. 

Interior Features of the Mack MD

The interior boasts premium satin aluminum trim, improved seating with lumbar support and enhanced LED lighting. New steering wheel controls for cruise control, telephone and audio functions have been added, increasing driver convenience and safety. All of these have been popular with Mack’s Class 8 customers.

Mack MD Standard Safety Features

The trucks now come standard with several enhanced safety features, including new ABS (Anti-Lock Braking System) with ATC (Automatic Traction Control), radio mute in reverse, and a park brake alarm.

Easier Connections for Installations

Pre-wired body builder connections, relocated air dryer, and updated wheelbases to industry-standard cab-to-axle (CA) dimensions make the updated MD Series easier to install an even wider array of body installations than previously.

More Vehicle Research

Thumbnail image for Work Truck’s “Trucks, Tips & Tours” featuring a Ditch Witch W8 hydro vac truck and presenter on a trade show floor. Bold text reads “Big Power. Smaller Package.” alongside a Truck Chat “Watch Now” button.
Vehicle Researchby Wayne ParhamMay 19, 2026

Ditch Witch W8 Hydro Vac Truck Walkaround

The Ditch Witch W8 hydro vac truck delivers serious hydro excavation performance in a more compact package than the larger W12. This walkaround video explains the Warlock Series’ direct-drive blower system, cyclonic filtration, safe excavation technology, and powerful vacuum performance.

Read More →
Orange Nissan Frontier PRO-4X overland build parked in a grassy wooded area with off-road tires, heavy-duty front bumper, winch, rooftop cargo storage, and camping accessories mounted above the truck bed.
Vehicle Researchby StaffMay 14, 2026

Nissan Frontier Overland Build Spotlights Real-World Truck Capability

Nissan’s latest Frontier build is aimed at overlanders, but the rugged platform and durability story could resonate with fleet buyers too.

Read More →
Cover of a whitepaper titled “The Hidden Costs of Departmentally Assigned Vehicles on Your Fleet” featuring a black fleet vehicle driving on a road at sunset. Subheadline reads: “Discover how your fleet can reduce costs and minimize risk by implementing vehicle sharing.” The document focuses on fleet optimization, vehicle sharing, cost reduction, utilization tracking, and risk management for fleet operations.
SponsoredMay 13, 2026

Why Fleet Managers Are Replacing Departmental Vehicles with Shared Motor Pools

Departmentally assigned vehicles often create hidden costs through underutilization, poor visibility, and increased administrative burden. This white paper explores how shared motor pool strategies help fleets reduce costs, improve accountability, and optimize vehicle utilization.

Read More →
Ad Loading...
Promotional graphic for a TruckChat video featuring the bright red Cummins X10 engine on a black background with bold text reading “Heavy-Duty Power. Medium-Duty Package.” Sponsored by Cummins.
Sponsoredby StaffMay 8, 2026

A Smarter, Right Sized Workhorse: The Cummins X10 Engine

Cummins’ new X10 engine delivers heavy-duty power in a lighter, more efficient package. Watch to learn more about specs, torque, PTO capability, and more.

Read More →
Screenshot of the Work Truck Solutions website promoting Ford Pro CVC dealer packages. The page features a commercial truck background image, marketing text about growing commercial business, navigation links, a consultation button, and an embedded YouTube video.
Vehicle ResearchMay 8, 2026

Work Truck Solutions Supports Ford Pro Commercial Vehicle Center Program

Ford Pro now requires all dealers participating in its 2026 CVC Program to maintain an active Work Truck Solutions subscription. Three different subscription packages are available to equip every dealer with the specialized tools they need.

Read More →
White box delivery truck parked outside a modern office building on a sunny day. The truck is photographed from the front angle, with chrome detailing reflecting sunlight and the building entrance visible in the background.
Vehicle ResearchMay 8, 2026

Hino Trucks Introduces its Le Series Battery-Electric Medium-Duty Truck

Hino Trucks debuted its new medium-duty battery-electric trucks at ACT Expo. The Le Series will be available in both 25,950-pound and 33,000-pound GVWR configurations.

Read More →
Ad Loading...
Interior view of Ford Super Duty Carhartt edition showing dark cloth seats with Carhartt logos and center console.

Ford and Carhartt Launch First-Ever Super Duty Package for 2027 Model Year

Ford and Carhartt unveil a new 2027 Super Duty package with work-ready upgrades, Duck Canvas-inspired interiors, and jobsite-focused durability.

Read More →
White Ford Super Duty pickup truck parked at a construction site beneath a Ford Pro Employee Pricing banner.

Ford Pro Launches Employee Pricing Initiative for Commercial Customers

Ford Pro launches employee pricing for commercial customers through July 6 on eligible Super Duty, Transit, F-150, Maverick, and Ranger models.

Read More →
Curtis Reed presenting a Chevrolet van at a trade show, highlighting GM Fleet’s commercial vans built for long-term reliability and upfitting.

Built to Last: Why GM Fleet’s Proven Vans Still Power Work Fleets

GM Fleet showcases Savana and Express vans’ proven reliability and the Equinox mobile service vehicle boosting fleet uptime and flexibility.

Read More →
Ad Loading...
Technician standing beside a work truck holding a hammer, with text “What makes a truck reliable?” overlaid

What Actually Makes a Truck Reliable for Fleets?

What makes a truck reliable for fleets? From uptime to maintenance and spec’ing, here’s what really drives performance, and where fleets can weigh in.

Read More →