Mercury - Quicksilver Shift Cable Bellows Kit Driveline Seal Flexible Composite 74639Q02. Overview. Water intrusion is one of the leading causes of damage to sterndrives, and the Mercury Marine 74639Q02 Quicksilver Shift Cable Bellows Kit is designed to stop it before it starts. This OEM replacement bellows fits MerCruiser drives with shift cables, forming a tight, flexible seal that protects the driveline from corrosion and water damage. Made from tough, convoluted rubber that flexes with your