GM Original Equipment™ Automatic Transmission Rear Output Shaft Seal by ACDelco®. Front. Inside Diameter: 1.77″. Outside Diameter: 2.441″. Thickness: 0.394″. Material: Rubber. Designed utilizing the latest technology, this product by ACDelco features premium quality and will perform better than advertised. Perfect for your vehicle and lifestyle, it is manufactured to meet or exceed stringent industry standards.