From 1915 onward, Ahrens-Fox identified its products with an alphanumeric combination of letters and numbers, which indicated the motor, pumping capacity, and equipment carried. This is where the 1917 Model MK 2 received its designation, Model M standing for a six-cylinder engine with a 750 gallon-per-minute pumper. The vehicle also features a specially ordered Holyoke pattern hose body, featuring flared sides and a divided seat on top to hold helmets and other equipment. A 20-foot rapid hoist extension and a 12-foot single roof with folding hooks were also added, as well as the famed Ahrens-Fox air chamber and multiplex pump.

In 1917, Ahrens-Fox delivered the Model MK2 Pumper to the City of Concord Fire Department in New Hampshire for $8,250.00. The brand-new pumper was assigned to Station No. 1 and was designated Engine One from then on. After its retirement from the City of Concord, the engine changed hands many times, until it eventually landed in the lap of restorer Nelson B. Barber of Downingtown, Pennsylvania.

Restoration began in 1978 – 61 years after the apparatus was produced. Barber replaced the pneumatic tires that had been added with time-appropriate hard rubber tires, as well as the rims. 24-karat gold leaf was also added by Ken Soderbeck of Jackson, Michigan to add a beautiful sparkle to the vehicle. Conn Instrument Company of Elkhart, Indiana added the last piece of restoration, a hard nickel plating to prevent tarnish.