Yeah...it's called the EPA. Same reason you don't see P-pump 12 valves rolling off the line anymore, and why you see DEF/DPF/SCR's on "new" trucks...

 

He didn't say Detroit's rolling off the assembly line, he said around. The biggest reason is the fact they're two strokes, shitty torque curve. And every one I've been around leaked oil like.crazy. dunno if its just the ones I was exposed to or if its a common thing. But compared to a 4 stroke diesel they suck. At least in stock form. Get the rpms up and they do great but getting a load moving is a chore

 

True, when a Detroit stops leaking that means it's out of oil

Ironically, the oilfield LOVES Detroits because most of the applications are power packs and Detroits have a FAR better power to weight/size ratio of their 4 stroke cousins. But, bear in mind that power packs don't give a poop about "curves" because they operate at a single RPM for hours on end. The smaller packaging, comparatively, allows for more compact power packs when footprint is critical...as in rig/boat/trailer space. Just $0.02