Update to make to my previous post, I did some reading up on the Sherman's, for identification if the shifter bolts on from the outside its a combo, if it is pinned on with an aluminium ball its a step unit. Also I did some reading on the gearing. The speed increase and decrease use clever gear ratios, the increase ratio is 0.669:1 (which means the input doesn't even go a full turn to spin the output once) which is about a 55% increase in speed. The decrease ratio is 1.517:1 (meaning it takes the input 1 1/2 turns to spin the output once) which gives about a 35% decrease.
These may not be exact stats but that's just what i've read on PDF's and Google searching.
These may not be exact stats but that's just what i've read on PDF's and Google searching.