Sierra International  18-8205 Transom Seal Kit The Sierra 18-8205 Transom Seal Kit is interchangeable with the following: GLM 21951, Mallory 9-72901, Mercruiser 30-803098T1. Each Sierra product meets or exceeds the original equipment part it replaces. Sierra Transom Seal Kit Meets or exceeds the original equipment quality Sierra part number: 18-8205 Interchangeable with the following: GLM 21951, Mallory 9-72901, Mercruiser 30-803098T1