Mikestem,
Your fire truck could have been from anywhere, but looking at the map, I see Camp Grayling was not too far away from Rose City. I was poking around on the web and found a historical society in the area that had info about the local fire department. You might check with Grayling FD to see if they ever had that truck in their inventory..they probably have someone one base that could tell them if it was stationed at the air base there.
The fire barn in the museum complex, constructed by members of the Grayling City and Township Fire Departments, houses two fire engines. The 1922 model truck is said to be the first ever used at Camp Grayling, and is on permanent loan from the 746th Battalion. Sgt. Major Chris Beauchamp and Sgt. First Class Terry Rood were instrumental in reconditioning the vehicle. The 1937 Chevy fire truck is a Champion Fire Engine made by W.S. Darley and Co., of Chicago. It was the city of Grayling's first fire truck. It was kept for old-time's sake until liability insurance became too high and it was put up for raffle. Mike McNamara won it; his father, Larry, kept it until a new home was found for it in the fire barn.