There was a fairly late model twin cyl. Horse for sale right around the corner from where I work with deck and snowblower, I believe. I wonder if it's still there? Right now he has a JD 365 (I think) for sale in nice shape. There's a guy I pass on my commute that has a twin Horse, too.
I grew up driving "vintage" tractors - my elementary school principal lived a short minibike ride away and I used to help him around his house, as well as his son, who was our superintendant and lived next door and had 30 or 40 head of beef cattle (as well as a daughter that was my age....

). The principal was newly retired, and had a 12hp Sears tractor late 60's/early 70's vintage, blue and white with the Tecumseh engine. That was a sweet machine! He bought a new Crapsman 16hp twin "lawn tractor" and the Sears service van spent more time at his place than anywhere else - it would vapor lock when hot and not start and they couldn't fix it. Finally it snapped off a rear axle shaft. He was not a large man, and it was a large, yet flat and smooth yard. This was around 1981 or so. I also spent a lot of time on a '57 Massey Ferguson 65 mowing hay. But my favorite was the Simplicity Broadmoor 707 and 728. Little bitty 3 blade deck (DEEP deck) and two speeds - slow and slower, and they pivot in front of the seat, not the front axle. VERY weird to get used to. But I've never had a better cut from a tractor.