Condition: Good used OEM condition came of running truck that got totaled out Description: Genuine Detroit Diesel 23535129 fuel check valve / fuel pressure regulator for Detroit Diesel Series 60 engines. OEM Detroit component used in the fuel return system to help maintain fuel pressure and prevent fuel drain-back issues. Part Number: 23535129 Applications. Detroit Diesel Series 60. 11.1L. 12.7L. 14.0L Condition: Good used OEM condition. Removed from a running application. Shows normal cosmetic wear from use and storage.