The Waterous Serial Plate should be on the Apparatus Operators Panel. If your apparatus is missing its pump panel serial plate, or never had one installed, the serial number may be found on the pump itself, the pump transmission or both depending on the vintage. For any CM or CS series pump a serial number plate can be found on top of the tank to pump connection. On some “Y” and “C” series transmissions, a serial number plate will be located in the lower left corner on the back of the transmission. In both instances, if the serial plate is missing, the number will be stamped into the case under where the plate was attached.