Genuine�Indmar OEM Exhaust Riser 3.5" Need 2 per engine (same part number for both sides). Fits GM 350,�305 raw water-cooled engines 94 & up 3.5"�ID exhaust hose.�93 & Up Corvette LT1 (Excluding�freshwater cooled) Must specify drilled and tapped�for extra hose connection