I thought their hype is that their engines are designed for marine use.

As for parts availability, I have found that Kubota is great. Virtually every country I have visited (Pacific and Caribbean Islands excluded) has a farm machinery supply that has Kubota parts in stock.

Having said that, the only parts I have had to buy this way are valve cover gaskets and filters. Other than an injector change, which I still ponder if I needed to do, checking valve clearances and a raw water pump rebuild are the only things I have had to do to my engine in nine years and 3000 hours.