Hey all - so I'm thinking that the Upper end of a #6 drive is where the direction of rotation is determined. Is that correct? So if I wanted to switch my props from spinning out to spinning in, then I need to swap the entire drives from one side to the other. Just swapping the lowers doesn't change anything right? Someone please confirm. Thanks!

I believe that is correct.

The old style #6 with the tie bar mounted to the back of the upper case the direction is done in the lower. The late #6 is done in the upper but the lower case drive gears must run the direction it was set to!