That's a good point also ..

I guess on a go-forward basis they are doing that. Diesels manufactured today are much more emmissions friendly than they were even ten years ago. Problem with diesel engines is they last so bloody long that a ten-year-old tractor is cheaper to fix than to replace when something goes wrong with it. I suspect we will see regulations in place to require trucks of a certain age to have advanced exhaust scrubbers installed ...

I guess another question in this regard is: Why isn't Yamaha (being primarily the only 2-stroke ATV manufacturer left) going into more technology to reduce emissions from their 2-stroke quads rather than just phasing them out. Bombardier has done it with their snowmobile lineup using direct injection .. why not have a DI banshee?