Hi Mike K., Thank you for sharing this review about the Differential Gear Set. Aftermarket products can be any part of a vehicle that is not sourced directly from the car's maker. These parts are direct replacement parts, designed to function the same, may not be physically identical to the original, but there are some instances that it even worked better than the OE parts. These items are just copied from the original which definitely have their pros and cons. The Return Merchandise Authorization was processed and the return instruction was sent to you via email. You may opt to use the courier of your choice for the return of the part. Once the warehouse received and inspected the returned item, the refund will be processed within 24-48 business hours, but the posting will still depends with your bank. Thank you.