The DM replaced the heavy duty B-model series by sharing the unique U-model offset cab on a newly designed deep section frame. The offset cab was a bold move for Mack in the industry. The offset cab resulted in a shorter bumper-to-back of cab dimension allowing for more cargo carrying capability. With the cab offset, the firewall and dogbox occupied floorspace that was seldom used by passengers. In vocational applications, the offset cab provided the driver excellent visibility along the left side of the truck. This was especially beneficial when backing into a paver, bin, or tight construction site. This truck was donated to the Mack Trucks Historical Museum by Republic Services in 2019.