dont know if anyone can help or not but im looking at this merc and the owner says that it needs some mechanical work and i ask him (via email) what is wrong with it. this is the reply in part that i got:
"I believe the problem is a glide rod, there is a rattle noise under throttle, the motor needs to come out for this to be corrected. i believe the glide rod is associated with one of the pistons"

now, what is a glide rod, what does it do, expensive to fix and can it be fixed yourself?
ive asked other V8 forums and no ones ever heard of it before.
what do you guys think?

Connecting rod (bearing) maybe??