1994 - 1998 5.9L Dodge 12 Valve
The 1994-1998 12 Valve Cummins is still popular because it is simple, mechanical, and easy to keep alive. Most owners shopping this page are dealing with age now; worn injectors, tired fuel parts, old turbochargers, leaking gaskets, and engine work on trucks that have already lived a full life.
Most upgrades on the 12 Valve platform still revolve around the fuel and air side first. Fuel system components, turbochargers, and exhaust systems are usually where owners start once the truck needs more towing power or better reliability. If you are looking at a crate engine or long block, check the build specs closely because not every 12 Valve replacement is set up for the same truck or power goal.