I'm guessing from what you posted that the valve body is not damaged. If that's the case, then you can buy a Valterra extension kit that has the aluminum rods and a plastic handle here:
https://www.amazon.com/Valterra-T104.../dp/B002N5J9HU
Or if the valve body and the rod are not damaged, and it's just the
"THREADED" "T" handle that is broken, you can buy them here:
https://www.amazon.com/Lasalle-Brist...0V64B0WP01TQHD
There are some handles that use a roll pin to secure the handle to the shaft, but I haven't seen one of them in quite a while. I'm guessing the end of your push rod is threaded ???