I'm a Yanmar guy myself....great little Diesel engines. Especially when used in tractors and turf care equipment. Of course, you can't get a Yanmar in a truck so that opinion doesn't really count here.
We have a 4 cylinder Cummins in our Case skid steer at work. It has so much power, the factory had to de-tune it for use in a skid loader. The engine was originally intended for use in a backhoe. Plus, at my old job they have a Cummins-powered Dodge work truck, and while it goes through transmissions about once every 100K, the engine has been bulletproof....