Hello Every body, the trouble I am having is my 718 D keeps cracking the Dis-Flex-Coupling for some unknown reason to me, I can not get a days cut with them, I have changed with NEW Parts, Dis-Flex-Coupling hub, Coupling connector, Coupling adapter, Coupling spacers, cap screws all bolts nuts and washers, I have put in all new from front to back, anyone have any idea why the are cracking. I am at my wits end, Thanks So Much for your help and your time. Marine