That should be the correct relay for your tractor.
If you want to check it out mount it with the battery hooked to the large post on the right ONLY.
With a test light see if you have power at the small post.
If yes ground this small post with a jumper wire and see if the relay clicks and you now have power at the large post on the left.
If yes it works.
If no at any point it is broken.
Just for fun if you do not have power at the small post with the battery hooked to the large post on the right......
Take a small jumper wire and jump from large post on right to small post.
Did the relay click now.
If so they sent you the wrong relay.
At least now you know if they sent you the wrong one or a broken one.
So now you know why I buy local.
Go to NAPA and ask for part# ECH ST53 Take 2 small pieces of wire with you if you want to test it before leaving the store.
Hook one small wire to the small post and the other to the large post on the right.
Now with a shelf battery in the store touch one wire to + and one wire to -. You should hear the relay click.