I used a WIX 51307 that I got at our local auto parts store.  This is same filter I took off.    After seeing the caved-in transmission oil filter when I took it off, I'm going to more diligent on changing it.  But, in my defense, I haven't had this tractor very long.

Chris - Thanks for the web site.  I haven't seen it before, and it looks like a good one.

Ronnie