The only difference was in the plastic hand grip. They had problems with that stamped gear and shaft, making minor changes. In mid 1956 they went to a cast gear that solved most of the problems. Make sure whatever tiller you use (5.5, 7.5, 10, 12, 15, 18, & 20 HP outboards) make sure the gear & shaft on the motor matches it. . . 😉
