Great motor. Not a Jeep expert, but I heard that the Jeep 4.0 L straight six is basically unchanged from the 1950's. People love it. It is a great example of how adding modern controls (MPFI) to an engine does wonders. Too bad the slant six never similarly transitioned to the modern era, though a few guys here are working on that. I understand the small block Chevy isn't much changed from the 1955 version other than improved controls.