I realize that the answers will be subjective, but I'm curious as to which Diesel Ram is the best performer between 2009-2012. I'm looking to purchase one from one of these years. Specifically, I'm looking for Crew Cab, LWB, Automatic Transmisson. One question... (For those with the DEF models) How often are you having to refill your DEF? I know practically nothing about Dodge Rams, but am looking to buy one soon, so any help or direction would be most appreciated. Thanks in advance, guys.