Broken manifold bolts

Hi, on my dads car It has two broke on the right side and one on the left. Or two broke on the left and one broke on the right. I do not really remember. I asked my friend he is a mechanic and he said the only way to get them out is to take the heads off and send them out. He said he has encountered where he tapped them out and the heads leaked coolant. I asked two other shops and they said the same thing. I am almost positive these are aluminum heads. They are also hard to get too. I just wanted to make sure that this is the case. Thanks for any suggestions.