Mercury - Quicksilver 815822A55 Complete Standard Rotation (RH) Gearcase Alpha One Gen II Sterndrives 2.00 Gear Ratio 815822A55. Overview. When your drive starts to show its age, the best fix is a true factory replacement. The Quicksilver 815822A55 Standard Rotation Gearcase gives your MerCruiser or Quicksilver Alpha One Gen II sterndrive a second life with the same performance and dependability it had the day it left the factory. Built for units with a 2.00:1 gear ratio, this complete OEM gearc