I need some help....I am in the process of buying a 1959 evinrude lark......the model number indicates that is is a long shaft.....35517.........when the seller measured from the bottom of the bracket to the cavitation plate it was close to 19 inches. I looked at a picture of a 1959 lark that had a extension on it and it was called a long shaft. My question, were 1959 evinrude larks that were sold as long shafts did they all accomplish the long shaft via the extension. Were short shaft motors the same as a long shaft motor except for the extension. When I look under a parts breakdown for both the 33516 (short shaft) and 33517 (long shaft) there is nob difference in the part numbers. Can someone please help. Thanks Cliff