Death of a /6

So what is it about #5 thats weak?

I bought a 75 Valiant once and the lady told me it had thrown a rod. I looked but couldnt see it.

I discovered the hole behind the starter,and another hole behind where the exhaust and intake mate together. The second hole was smaller,from schrapnel coming off #5. I still have the piston and S shaped connecting rod that came out of #5 as a keepsake because I couldnt believe a 225 would quit.