What parts are in a wet kit for semi truck?

You'll have a PTO, which will either be run off of the flywheel or the crankshaft.... there'll be the means of actuation, which could be a lever which goes through the floorboard, an air actuated solenoid, or an electrical solenoid. There'll be a hydraulic tank, hydraulic filter, the actual hydraulic motor, and you may or may not have a hydraulic oil cooler, which may have its own fan.