Hi Bob. Here in Albuquerque we use the same criteria as FDNY. Engines are black shields with white numbers. Ladders/Trucks are black shields with red numbers, squads are black with yellow numbers and the rescue/ambulance has blue numbers. For the company office the color scheme is reversed; engine LT has a white shield with black numbers, Truck Captain has a white shield with red numbers... ranks are indicated by the appropriate number and configuration of trumpets located at the very top arch of the shield.