here you go, but it doesnt look like a separate part so youcan only get it as part of buying the whole tranny
https://www.partstree.com/models/yta-22v46-960450051-00-husqvarna-46-yard-tractor-2015-07/drive-2/
you have only 2 choices left, buy a new tranny, or buy a parts mower and take that tranny, or the parts you need from it, off to fix yours
then maybe there is still a 3rd option is someone on ebay might be selling that part you need used
and in the future remember your lawnmower transmission is weak as shit and not designed to pull anything around more the a small lawn cart with 25 lbs load in it