Dorman 579-003 Fuel Tank Sending Unit Lock Ring

Fuel Tank Sending Unit Lock Ring

Dorman 579-003 is a metal fuel tank sending unit lock ring used to secure the fuel pump and sending unit assembly to the tank opening. It is recommended for replacement any time the sending unit is serviced, helping restore a tight, dependable retention point on the fuel system.

Compatible with a wide range of Ford, Mercury, Jeep, and Lincoln applications, including Ford Mustang, F-150, Bronco, and Jeep CJ5/CJ7 models that use a 2 in. inside diameter lock ring. The Dorman 579-003 fuel pump lock ring is built for direct replacement service where the original retaining ring has worn, corroded, or lost its grip.

• Metal construction for durable fuel tank service
• 2 in. lock ring diameter with 1.875 in. inside diameter
• Outside diameter measures 4.25 in.
• Gasket or seal included for service convenience
• Direct replacement for select Ford, Mercury, Jeep, and Lincoln fuel tank assemblies
• Cross-references Spectra Premium LO03 and OE-style part C0AZ9A307B

Detailed Application Coverage

This fuel tank sending unit lock ring is used to retain the fuel pump assembly at the tank lock opening on many classic and late-1970s through 1990s vehicles. It is a practical replacement for service work on Ford Mustang 1964-1973 and 1979-1997, Ford F-Series trucks 1975-1984, Ford Bronco 1978-1984, Ford E-Series vans 1975-1985, Jeep CJ5 1973-1983, Jeep CJ7 1976-1986, and select Lincoln and Mercury models. Dorman 579-003 helps restore secure retention where the original ring no longer holds the sending unit firmly in place.

What It Helps Fix

• Loose or damaged fuel pump retaining ring
• Corrosion at the tank opening
• Poor sealing after sending unit service
• Fuel pump assembly movement at the lock ring interface
• Repeat service caused by a worn original ring

Installation Notes

Inspect the tank flange, sending unit seal, and locking tabs before installation. Replace the ring whenever the sending unit is removed for service, and confirm the 2 in. I.D. specification matches the vehicle’s fuel tank opening. Use care during installation to ensure the ring seats evenly and fully locks the assembly in place.

Quality Assurance

Dorman manufactures this lock ring from durable metal materials for reliable service in fuel system repair. Part number 579-003 is built as a service replacement for select applications where a secure fuel tank sending unit retainer is required.