Suntec model identification charts will help you identify and select a replacement. Be sure to match rotation, RPM speed, nozzle firing rate, and mounting configuration when selecting a new unit. Call the factory if you need assistance. Once the gage is installed, you can turn the pressure adjusting screw in or out to increase or decrease pressure accordingly. Just as the pressure gage is connected to the discharge side of the pump, a vacuum gage is installed on the suction side of the pump.
All pumps have two inlet ports.
Install the vacuum gage in the inlet port that is not being used.