A minimum parts bypass plunger includes a main shaft or pushrod extending through a hollow plunger body that incorporates flow passages formed in the adjacent surfaces of the pushrod or the internal bore of the plunger body. The pushrod is retained within the plunger body by respective head and tail pieces or caps that are locked to the plunger body by 360 degree crimps around the head and tail pieces. A one piece clutch is supported in the head piece. The pushrod, has an integral valve head that closes the flow passages when seated against a seat in the plunger body.