Nope. If you did, I'm pretty sure the EPA would shut you down. Emissions regulations aren't quite as strict for tractors as for cars and trucks, but they are headed in the same direction. I don't think it's possible to meet emissions without computerized controls. And once you've put hundreds or thousands of dollars worth of electronics on the tractor, it's hard to resist the temptation to add DRM.

I think that you would have a hard time getting EPA approval if you starting making brand new copies of legacy engine designs. A new diesel tractor engine has to meet EPA Final Tier 4/ Stage IV standards. I don't know what would stand in the way of making a knock off of the 4440 chassis and transmission that uses a new Cummins or other crate engine though.