CUMMINS 3943300 OEM VERTICAL WATER NECK (WATER OUTLET CONNECTION) – RAM 5.9L/6.7L (2003–2009)

Product Description

The CUMMINS 3943300 OEM Vertical Water Neck (Water Outlet Connection) is the factory-engineered coolant outlet used on 2003–2009 Ram 5.9L and early 6.7L ISB engines. This genuine Cummins outlet maintains proper coolant flow direction from the thermostat housing to the upper radiator hose, ensuring the system operates at OEM cooling efficiency. When your original outlet becomes corroded, pitted, or warped, this replacement restores a leak-free seal and precise hose alignment for long-term reliability.

Because this part controls the main outlet path from the engine’s thermostat housing, proper sealing and geometry are critical. This OEM casting eliminates the fitment issues and coolant weeping commonly seen with aftermarket copies. Built to Cummins specifications with correct bolt pattern, neck angle, and sealing surface integrity, it installs cleanly and integrates with factory hardware without modification.

Fitment

• 2003–2007 Dodge Ram 2500/3500 5.9L ISB
• 2007.5–2009 Dodge Ram 2500/3500 6.7L ISB (early years; verify ESN)
• Also used in certain Cummins ISB/QSB industrial cooling packages (verify ESN before ordering)

Cross-Reference / Related Cummins Parts

• Replaces / supersedes: 3943301, 3943302 (verify by engine serial number)
• Thermostat housing (mates to this outlet): CUMMINS 397xxxx (add link once product exists)
• Thermostat (commonly replaced at same time): CUMMINS 5292724 OEM THERMOSTAT
• Coolant temperature sensor (often replaced during service): CUMMINS 4088832 OEM COOLANT TEMP SENSOR

FAQ

IS THIS A GENUINE CUMMINS WATER OUTLET? Yes. The 3943300 water neck is an original Cummins OEM casting and not an aftermarket reproduction.
WHAT YEARS DOES THIS FIT? It fits 2003–2007 5.9L and 2007.5–2009 early 6.7L ISB engines. Always verify by VIN or ESN.
SHOULD I REPLACE THE THERMOSTAT AT THE SAME TIME? Yes. Cummins recommends replacing the thermostat and O-ring any time the water outlet is removed to ensure proper sealing.
DOES THIS COME WITH A GASKET? No. Order the correct Cummins thermostat housing gasket separately to prevent leaks.
ARE THERE ANY SUPERSEDED PART NUMBERS? Yes — the 3943300 replaces earlier revisions such as 3943301 and 3943302.

Specifications