My brother is offering me his 2004 grand Cherokee with a 4.7 engine. Problem is, it has a coolant leak and needs new head gaskets. Looks like a pretty big job. Reading these 4.7 motors seem to be pretty common problem. Anyone done this job ? Is it a good fix, ie or does it come back again ? Average cost to do the job yourself ? The jeep has 130k on it. wandering if worth my while to fix and put my kid in it. any advice or input thanks.