Replace Toyota Sienna Transmission For Sale. Discover Toyota Sienna Automatic Transmission Parts Catalog & Toyota Sienna Transmission Assembly Lube. Maintaining the transmission of your Toyota Sienna is crucial for a smooth driving experience, with timely fluid changes and avoiding harsh driving being key to longevity. Signs that your transmission may need replacement include slipping gears and a burning smell. Opting for a genuine OEM or high-quality aftermarket transmission ensures compatibility and durability. Each type offers unique benefits, with OEM guaranteeing manufacturer standards and aftermarket options often providing a cost-effective alternative. When installing, a professional fit is recommended to ensure peak performance. Shop with confidence for your Sienna transmission needs at our online store, where quality meets convenience.