ZD 331, 60" deck, bought it used.
3PK Oregon 96-363 Gator Blades fits 60" Kubota ZD21 DZ28 ZD323 ZD326 ZD331 ZG327.
Copy and paste this to ebay, you can look at the ad. They are .050 thinner than the Kubota blades.
Did a google search, seems to be a known issue.