The A-Drive Motor Round Dust Cover fits both 40:75 & 40:90 A-Drive direct drive gearboxes before 2018. Made from cast aluminum. Includes (4) 1/4 in. mounting holes. Mounts to the outside of the motor reducer. Protects from dust and debris. The A-Drive Motor Square Dust Cover fits both 40:75 & 40:90 A-Drive direct drive gearboxes. Made from cast aluminum. Includes (2) 1/2 in. mounting holes. Mounts to the outside of the motor reducer. Protects from dust and debris.