I have worked on tons of them and everysingle one that dropped a valve the owner confessed to it overheating first. Tom is the first one I heard the owner deny it. I can not find any difference in the heads from 03-08 looking at a dozen of em I have on the shelf so if there is a change someone would have to explain how to tell the difference cuz I don't see it. I have seen a lot of broken valve springs ocasionally starting at 100K but more common after 150K of course it depends on how they are driven, maintained, luck... even the newer ones up to at least 2012 I have seen break springs, don't know why they made valve springs that didn't hardly ever break for nearly 100 years then all of the sudden its an issue. Water pumps start leaking, again been building em 100 years and they can't figure out how to make it not leak. Also I have seen shattered rods in jeeps 1/2 ton and 3/4 pickups also so I am not convinced of the cowl being the problem. The first one I came across was in a very well maintained durango parked in a garage, ran great when it was parked, they started it to warm up and came back out and it was knocking and had punched a hole in the side of the block. I really wanted to run a set of the early pistons in my 2011 engine but I have seen so many of those early rods snap for no reason I couldn't bring myself to do it, I am terafried of em. I just bought a 2004 durango for my wife in mint condition but with a hole in the side of the block, I am gonna see if the machine shop across the street can swap the later rods in without breaking the pistons and I am gonna run the later eagle top end.



They are interfearance engines.