Walker MDGHS21DH 21HP Model D Mower with GHS, Kubota D722 Diesel Engine, and Hi-Dump®. The Model D is designed with the same footprint as the Model T, making it compact and capable of mowing both small and large properties while also boasting a transverse mounted, 3 cylinder diesel engine and liquid cooling. A self-cleaning, reversing radiator fan keeps the Model D cool and efficient even in the toughest conditions. Weighing in just under 1,200 lbs, the Model D is one of the lightest diesel-equipped commercial mowers on the market.