Hi, I have 71 240z for about a year. I took it to the mechanic for cluch problem and the guy found out that there is a leak from head gasket and its burning the coolant in cylinders. So, I asked him that how much would that be for replacing the head gaskets and he said that'll be $650~700. Since I'm not good at mechanics, I don't know if it is average price or I may be able to find cheaper way or do it my self with reading a manual. Any advise is appreciated. Thank you.