MerCruiser 220-2282 GM 6270046N Flywheel 1963-1978 120hp 140hp 2.5L 3.0L 110hp New Parts 3" opening on bottom for

3" opening on bottom for 2-barrel 3" Throat Rochester Carburetors that were found on V-Engine models from this time period

so I'm not sure if that had something to do with their casting of these when they were new

Engines AQ120B

Came off  a 80's Rinker Unsure Year

There are some markings around the pinion area internally

MerCruiser 220-2282 GM 6270046N Flywheel 1963-1978 120hp 140hp 2.5L 3.0L 110hp New Parts 3" opening on bottom forPart Number(s) Included MerCruiser 220 2282 Crankshaft Flywheel GM 6270046N 6270045 (which sometimes looks like 6270048N) General Application Compatibility GM 4cyl 2 PIECE REAR MAIN SEAL ENGINES GM 110hp 4cyl 2. 5L 153cid 1963 1966 GM 120hp 4cyl 2. 5L 153cid 1964 1978 GM 140hp 4cyl 3. 0L 181cid 1968 1978 This is a bit thicker than flywheels found on later MerCruiser 4cyl engines (see other listings for the later versions) 12 3 4" Diameter 153 Tooth 3.