i have a 02 cummins 24v just got a air dog2 150 adjustable pressure any way i took off the filter and pump changed the fitting going into the injector. my mechanical gauge connected to the fitting i changed going in the injector pump what type of gauge i need now or where do i hook it up?

 

You need at least a 0-30psi fuel pressure gauge. You will also need a fuel pressure snubber fitting or isolator. It will tie into the inlet on the pump.