This is a NEW Stanadyne electronic injection pump for the John Deere 6420 tractor with the 4045HL270/271 engine. It is manufactured by Stanadyne, the OE manufacturer of this pump for John Deere. The John Deere P/N's for this pump are RE518086 or SE501234. Although it is a new pump, the original core must be returned. CORE CHARGE: A core charge of $250.00 will be applied to your credit card account, if the core is returned within 30 days you will receive credit. Feel free to call our parts department at 800-891-8038 with any questions or if a conflict should occur.