Mercruiser 863903A01 Heat Exchanger Replacement 8.1L Replaces Mercruiser part number: 863903A01, 863903T Suits Mercruiser engines: Various 8.1L (496 MAG) engines Specifications: - 4" diameter- 22" Length- 2x 1-3/4" coolant hose connections- 1x 1-1/4"...