Before I found a Merc tool for the flywheel nut for the K series motors I used a 15" Crescent wrench which will work fine, Please don’t use a Pipe Wrench on the nut. All you OMC guys are spoiled using your 5/8, 11/16, and 3/4 sockets. Until you have run a KG-7 Hurricane motor on a 12′ or 14′ aluminum boat you haven’t lived.