How to Securely Buy Used Transmission Online Following the correct procedures can make purchasing a used transmission online easy and safe. Determine the brand, model, engine size, and transmission code of your car first. Use this knowledge to look for trustworthy internet markets for auto parts or used transmission dealers. Seek out comprehensive product listings that contain warranty coverage, compatibility information, mileage, and condition reports. Verify if the vendor provides technical support and has a clear return policy. When done correctly, purchasing a used transmission online offers a quick and easy way to compare rates, access a large inventory, and have your car back on the road sooner.