Yamaha Casing, Lower - 61A-45301-03-4D. High-Quality Lower Casing for Yamaha Engine Protection and Performance. The Yamaha Casing, Lower - 61A-45301-03-4D is a reliable and essential replacement part designed to protect and house the lower components of your Yamaha engine. Constructed with durability in mind, this lower casing plays a crucial role in safeguarding the internal engine parts from water, debris, and other environmental factors that can lead to damage or corrosion. Its robust design