Quote
There is zero evidence suggesting the Fredo knew about the hit.


It's a murky situation all the way around - what Fredo was told, what he was offered, what he finally did. I tend to think now that Coppola and Puzo reached a place in the script where they realized that explaining the hit would result in the audience cheering when Fredo got his, so they just went silent about it.

"All of these men were good listeners; patient men."