Sierra 18-7721 Mercruiser Fuel Filter Replaces 35-864572 Sierra replacement fuel filters are designed to meet OEM specifications. All Sierra Fuel Filters not only protect your engine, but are also over 90 efficient at removing engine damaging 10-micron and larger particles without starving the engine for fuel. This fuel filter fits Mercruiser MPI EFI engines with boost pump, 8.1L 496 CID for 38 I.D. Fuel Lines. Interchangeable with Mallory 9-37826 Mercruiser Stern Drive 35-864572 35-864572T 35