I am in need of a better source of repair information. I have a 72 model 50 HP Johnson<br />Model#503SL72C Ser# E3645408. Any ideas on where to get wiring diagrams and system type (ing,charging, etc.) Spent 40.00 today on "Clymer's OFFICIAL Shop Manual" and it show them for 50 HP. For that matter it does show a 50 HP in 1972. Thanks for help given. <br /><br />Sorry I am Terrible at typing. it does not show a 50 hp for 72. Also the model number is stamped on the tag as above. The sales man at the local marine dealer questioned it also!?