Unibody bypass plunger and valve cage

A bypass plunger, comprising:

• a cylindrical body comprising:
• a first end,
• a second end opposite the first end;
• a hollow inner bore that extends from the first end to the second end,
• a first opening at the first end that allows fluid to flow into and out of the hollow inner bore, and
• a valve cage having a valve seat formed adjacent the second end;
• a valve dart that is movably mounted within the valve cage, the valve dart comprising:
• a valve head having a sealing face that is configured to engage the valve seat of the valve cage, and
• a stem that extends from the valve head, wherein a portion of the stem has a uniform surface profile that includes a plurality of alternating ribs and grooves, wherein the ribs have a radius of curvature R1 that is between 0.02 inches and 0.15 inches, wherein the grooves have a radius of curvature R2 that is between 0.02 inches and 0.15 inches and wherein a spacing S between adjacent ribs and grooves is between 0.02 inches and 0.075 inches;
• a clutch assembly mounted around the stem of the valve dart;
• and
• a retaining nut having one of external threads and internal threads, the other of external threads and internal threads being formed on the second end of the cylindrical body, wherein the retaining nut is secured to the second end of the cylindrical body by the external and internal threads.