Like John K said the large 800 lb spring applies the presure to the direct clutch in the O/D unit and all power goes throught the direct clutches in first , second and third. It does also have an overrunning clutch in the overdrive that holds if the direct clutches slip. It actually has that overrunning clutch (sprag) to prevent shift flare going from third to overdrive but it would hold if the direct clutches slip. I just dont really know how much power it can handle. Ron