I am the first one to admit my ability to visualize machinery in 3D is greatly lacking so please keep that in mind when deciding how much weight to give to these comments.It would have to be the input-shaft or output shaft gears… the side gears would not accomplish that.
In the mower gear boxes like the one for the RC48 deck, there are only two gears. This differs from 3 pt hitch style snow blowers where there are two outputs from the gear box. One output for the fan and a second for the auger. These two outputs are at 90 degrees from each other and these gear boxes must incorporate more internal gears than a mower deck gear box.
When the issue of reversing rotation first came up many years ago, I had trouble picturing the internal workings in my mind.
I bought educational model parts so I could easily play with the possible variations on my desk instead of fighting with oily. greasy parts.
These are my simple models showing how the relocation of one gear reverses the output shaft rotation.
I realize the relocation of an internal gear will not be as simple as in a model. Machining may be needed. My point if to provide a possible soultion if nothing else works.
I have in my files this company who is/was making pto reversers in the USA.
pto reverser
Dave