Abstract: A diaphragm-type gas pressure regulator wherein the valve subassembly is constructed as a drop-in unit. The valve subassembly includes a diaphragm lever and a plunger valve. A seat disk is inserted in a cavity at a first end of the plunger valve and the rounded pivot end of the lever is inserted in a groove at the other end of the plunger valve. The plunger valve is then inserted into a valve guide and a lever pin is installed through the guide and the lever, thereby capturing the subassembly. This subassembly is then placed into the regulator body and a mounting plate of the valve guide is screwed down into the regulator body. The lever is lifted up and its actuator end is inserted through an opening at the bottom of the valve stem of the regulator's diaphragm assembly. An orifice member is then threadedly installed into the regulator body inlet, the end of the orifice member having a valve seat which becomes seated in the end of the plunger valve guide.