I'm surprised people forgot about the valve seat issues the 4.7L has. Normally not a big deal but if you get one of these 4.7Ls hot ONCE you WILL drop valve seats out of the head. I have seen so many of them do this. Even the Gen 3 Hemis do this but not nearly as bad. The 4.7L has problems with bad exhaust studs breaking in the head. You can help fix that by putting on a flex joint in the exhaust. They typically sludge up easily because people don't do regular and meticulous maintenance that they require. Other than that they aren't bad engines and are more fuel efficient then their other V8 counterparts 5.2/5.9.

The 3.9 is a bullet proof engine for the most part, but it lacking in power and eats almost as much gas as a 5.2L. Great motor but no guts IMO. You might have to replace a belly pan gasket and that's it. I would suggest getting a 5.2/5.9 if you can.