The serial number on transom plate and stamped on a wlech plug on the power head identifies the outboard and indicates if their are unique parts or if internal changes have been made during the model run. The serial number should be used when ordering any replacement parts for your outboard. Starting with the 1980 model year, the model designation is coded. The last 2 letters of the model code indicate the model year. To determine the year of a given model (1980-on), write the word INTRODUCES. Below the word, number the letters 1 - 0. Match these numbers to the last 2 letters of the model code. As an example, J25TELCT is a 1983 model. The "C" represents 8 and the "T" represents 3.