Yamaha - Gear - 6D1-45571-00-00Yamaha Gear Lower Unit Gear 6D1 45571 00 00 Overview When you're inside a Yamaha lower unit, you realize pretty quickly that every gear has to pull its weight. This gear is part of that system that keeps everything turning smoothly when youre shifting and running under load. Ive worked on setups where a worn gear threw off the whole feel of the motor, from noise to performance. Replace it with a solid one like this, and you get back that smooth,