Welcome to the site.
Please post a picture of one of the broken ones, closeups if possible. A picture of how it mounts would be handy.
You say it snaps, you would expect it to bend really. Is it the rod, or the rod ends that are breaking?
Deere are quite good at stepping up to the plate when there is a problem.
Are you installing the new rods or is the dealer doing it? If something is bent or binding that would cause repeated breakage