Detroit Diesel Spec Manager Spec manager software sets up and compares various vehicle specifications to fine tune drivelines saving time and money. This fun and simple-to-use tool can help you determine what driveline specifications fit your needs. With spec Manager, a service person can troubleshoot a low power problem. Simply choose engine, vehicle, transmission, tires, and rear axle ratio and spec manager will determine the vehicle's fuel economy and operating performance. spec manager can even predict the number of shifts to be made on a trip and the fuel economy before purchasing a truck. Develop and troubleshoot tailor-made truck specifications for your customers with this easy-to-use vehicle specification software.