I don't know which drive you have, but this is from
www.sterndrives.com:
Alpha One 5-01301017 1.30
Alpha One 5-01471017 1.47
Alpha One 5-01622017 1.62
Alpha One 5-0181017 1.81
Alpha One 5-01941017 1.94
Alpha One Counter Rotation 5-5000177CP 1.47
Alpha One Counter Rotation 5-5000162CP 1.62
Alpha One Counter Rotation 5-5000181CP 1.81
Alpha One Counter Rotation 5-5000194CP 1.94
Alpha Gen II Counter Rotation 5-5111200LP 1.47
Alpha Gen II Counter Rotation 5-5111300LP 1.62
Alpha Gen II Counter Rotation 5-5111400LP 1.81
Alpha Gen II Counter Rotation 5-511500LP 1.94
Alpha Gen II 5-5121200LP 1.47
Alpha Gen II 5-5121300LP 1.62
Alpha Gen II 5-5121400LP 1.81
Alpha Gen II 5-5121500LP 1.94
Alpha Gen II 5-5121600LP 2.00
Alpha Gen II 5-5121600LP 2.40
To be POSITIVE about what ratio you have you must count the teeth
on the upper gears. Don't always trust stampings.