Late to the party here, so I don't expect this to get a lot of traction, but I'd like to point out that part of the reason this hasn't existed until recently as an option in the US is because it's functionally illegal for it to exist.

> The 12-valve Cummins is arguably the most widely understood diesel engine in North America. Every independent shop, every shade-tree mechanic with a set of wrenches, every farmer who grew up turning bolts has encountered one.

That's great! I'd point out the 12 valve wasn't introduced until the 90s, but that's kind of immaterial -- it's as simple to work on as any other mechanically injected analog diesel is and they were in widespread use for nearly a century before that. One immediately wonders why we moved away from these and towards more complex options, and why this startup has to remanufacture old engines instead of sourcing new engines. The answer among those of us who care about right to repair tends to be "evil corporations want to make proprietary systems that require ongoing fees!" which is true for John Deere, but also, the EPA mandated DEF/DPF systems + limp modes on all farm equipment since 2014, and the new relaxed standards include complicated rules about what percentage into limp mode they go at different intervals during different periods of time after those notoriously unreliable systems start to have errors. You can't do that without modern ECUs!

I'm all for reducing the harm caused by running diesel engines in the most densely populated cities on the planet (DEF and similar systems are about particulate emissions, not carbon), but we're being naive if we pretend that extending these regulations to farm equipment isn't a huge factor in why that same equipment has gotten more expensive and less reliable over the past decade.