These end caps are the highest quality on the market we utilize High Grade Aluminum with great corrosion resistance as well as a hard anodized finish for durability and another layer of corrosion resistance from the harmful environment. We also utilize a Viton oil seals which is the highest quality material available for the application insuring the rebuild is only done once for the remaining life on the engine. We believe if you are going to do something it better be done right the first time. These Caps fit Generation 1, 2&3 3 ram style trim units. 1100- 8M0021648 OEM 99638A1, 8M0021648