An improved system and method for mounting an air dryer is provided. The improved system and method employs a single centralized special fitting that secures the air dryer manifold to a reservoir. The bore in which the fitting is disposed is used to communicate air from the reservoir to the air dryer in order to purge the desiccant in the air dryer. The mounting assembly includes anti-rotational mechanisms which prevent the air dryer from rotating about its axis. The mounting assembly may also include a reservoir and a mounting bracket for the reservoir which uses less than 75 percent of a truck mounting rail height.