todd,I have been a marine mech for 30years. have seen exactly the same break your dealing with. our machine shop does a process where they use pins that overlap themselves. it is a great system,check it out!! they even do freeze cracks on our engines and they pressure check and guarantee it. those v-6 motors are very prone to " run on"=there are many things that can contribute to it.if you want to talk to me I'd be happy to help,even if its just over the phone. don't mean to toot my own horn,but I have ALOT of experience working on boats,and I can give you my thought on your options.p.m me with a number,I'll call. if you want to verify my credentials,look on boatreeds.com I'm randy