Abstract: A hydraulic dry power take-off clutch is adapted to be retrofit for prior manually actuated dry over-center power take-offs in compliance with certain SAE specifications. Both the resultant clutch and a retrofit kit for effecting the same are presented. According to the invention, an input hub is securedly received upon a shaft with an end plate secured to the input hub. A drive flange is adapted for securement to a flywheel or power source. A hydraulically actuated clutch disk assembly is received by the input hub and is in interconnection with the dry flange. Finally, a rotary union is received upon an end of the input hub opposite that of the clutch disk assembly, the rotary union providing a conduit for passing pressurized hydraulic fluid to the clutch disk assembly. The entire structure is adapted to be received within the same bell housing, and to employ the same drive ring as the prior art dry over-center power take-off units.