I've been looking at the Ram and found one I liked, drives great and loved the interior compared to my 07. I also drive a Ford 250 diesel torch shift and wow Its quick and noticeable extra horsepower....
GM did at one time have a plant in Mexico. We used to check the El Caminos as they came across the border at the train bridge, not for Customs, but looking for folks hiding in the cars.
So Ram is at least not the only US to build cars there.