The D19 is a great tractor. It was made from 1961 to 1964. Both gas and diesel versions used AC's 262 ci 6-cyl engine. The gas version was 71 HP while the turbocharged diesel was rated at 66 HP (a conservative rating). If you go gasoline, better get a fuel tanker, as the big gas six was pretty hard on fuel. We have a 1964 D19 turbodiesel with factory 3-pt hitch and dual hydraulics and it's great to bale hay with. The D19 was the predecessor to the 190, one of AC's best. If you're looking for a newer, bigger, and better tractor, consider a 190. I also have a 190XT Series II and there is a world of difference. Anyway, there were no major design flaws or weaknesses that I know of. It's a very dependable, durable tractor. In central Missouri, a nice D19 diesel will range from $3500 to $4500. I've seen gas models range from $2000 to $4000. The factory 3-pt hitch and dual hydraulics are also a factor.