4010 Mule tranny rotation direction confused
 

So after downloading many manuals, I still can't figure out when and how the inner/outer drive shafts interact or engage each other. Is the outer shaft always engaged by the high gear and thru the reduction gear within the hi low gear mechanism ? This has to be true because the fw/rev shifter has to engage this outer shaft at all times?Or is the outer shaft engaged only when in low gear? What happens in low gear??does reverse work in high gear...? Does the hi low shifter actually change what output shaft rotates? I know I'm close to understanding, but need clarification