1. The door says Cummins turbo Diesel on 12 valves; Cummins 24 valve turbodiesel on 24's
2. the 12 valve has an inline injection pump with the 6 injection lines, in a line front to rear, and crossing the head to exposed injectors on the passenger side. the 24 valve has a little injecton pump with the 6 lines coming out the back of it in a circle, going to the side of the head on the driver's side.
3. 12 valve has 6 little valve covers with a tin cover over them. 24 valve has a one-piece valve cover that says 24 valve. . .