It feels like theres 4 hols in the back of each head. Which one is for the coolant crossover tube? And do the other holes need to be blocked (will coolant leak out)? I'm asking because I just started my car after rebuild and coolant was leaking from rear of heads, not sure if I used right holes or if I need new gaskets or what not. Help please

 

You can see from this pic where the steam pipe goes. The other holes are mounting holes, not cooling passages.

 

Thanks shoebox. I must need new gaskets.