My wife went and bought a 2003 4.7 ram 1500 for oldest daughter, and ignored me insisting on having a real mechanic look at it. so she drives up and i instantly suspect a head gasket leak. Took it to a shop and of course it does need head gaskets and machining. the shop said we should replace the timing chain set..... there's about 150k on it. is this really necessary? I heard of t-belts breaking but never heard of a chain breaking. anyone with a high mileage 4.7, your input would be greatly appreciated.... probably only have the vehicle a few years as she is a junior in high school and school is 20 miles round trip. thank you!