This is the older of the 2 ZD21 mowers we have.
60 inch cut diesel with turf tires for summer and a set with more grip for winter.
I love it. The speed and manuverability is excellent, fuel economy good, hill climbing good. Much of the areas we mow have had cattle during summer so the ground is not flat as a lawn, while we could do with some suspension, the ride on lower pressure tires is not too harsh.
When the opportunity for a newer ZD21 came up we got it. 2012 42 inch 21hp with a hydraulic rear mounted catcher what fun and an excellent job. Highly recommend Kubota.