Mack Trucks adds new rear axle, engine rating to Mack MD Series

Mack Trucks now offers a 23,000-lb. rear axle and Cummins B6.7 engine with up to 325 hp on its Mack MD Series models. The heavier axle is designed for a Gross Axle Weight Rating of up to 23,000 lbs., and when working with the Cummins B6.7 engine and Allison 300RDS transmission, the Mack MD Series can handle increased towing capacity with 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 MD Series includes the Mack MD6 and the Mack MD7, which each have a Gross Vehicle Weight Rating of 25,995 lbs. and 33,000 lbs., respectively. The vehicles can serve for dry van or refrigerated applications, as well as stake or flatbed trucks and dump and tank trucks. Now, the heavier rear axle and engine rating also makes the truck bodies ready to serve as refuse packers with 11-yard up to 20-yard rear loaders or as water trucks.

The MD Series (for medium-duty applications) comes in 4x2 configurations and both models offer sharp wheel cuts for maneuverability. The cab is larger as of January 2025, with a bumper-to-back-of-cab measurement of 107”, and the trucks come standard with an Anti-Lock Braking System, Automatic Traction Control, a parking brake alarm, and the ability to mute the radio while reversing. Additionally, the interior has a satin aluminum trim, LED lighting, and new steering wheel controls for cruise control, telephone, and audio functions.