If you can't find a replacement, you might consider:
-taking it apart and cleaning the contacts inside. Depending on it's construction and how careful you are at getting it apart, it can work like new again.
-looking at the wiring diagram for the tractor, to see which connection goes where, as if it's a standard 4 post relay, you can get spade connectors and wire up a regular 4 post relay of sufficient rating. It won't look as nice, but it'll work just fine.
-taking it apart and cleaning the contacts inside. Depending on it's construction and how careful you are at getting it apart, it can work like new again.
-looking at the wiring diagram for the tractor, to see which connection goes where, as if it's a standard 4 post relay, you can get spade connectors and wire up a regular 4 post relay of sufficient rating. It won't look as nice, but it'll work just fine.