Rebuilding an '84 4d55t to put into my '91 Power Ram 50, and the pump needs some work. The throttle control lever is busted, and the plunger shaft is scored very badly(probably part of the reason the lever broke). To get the thing running we need to rebuild the pump, and while we're at it upgrade to a 12mm plunger. So my question is where do I go about getting one?