I was looking at the 3rd picture....that tooth gear and by the looks of it all the breaks look clean but the lower left gear....looks like its been crack there for awhile since its not shinny or bad light from the picture.
I priced out a tranny at my kubota dealer a few years ago as they were replacing one and I thought they told me 4500 for a new tranny.
Seems like today if much breaks its cheaper to replace the unit than have it fixed with labor these days....if doing yourself might be cheaper....but you know how much they get for parts...you may be beating r head against a rock.
I know in car and truck trannys if you take the pan off and there is parts in bottom of the pan just put pan back on and by a rebuilt or new tranny today as parts are outa site.
Art