I'm in the market for a 4th gen, would like to spend no more than 20k. I can get a 50k mile 2005 limited V8 or a 2006 V8 sport... are the 06 upgrades worth having, or should I go with the 05 limited for the leather, navi, heated seats etc... I'd prefer the loaded truck but if the 06 changes are a huge difference, I'll take the newer truck. Any info would be greatly appreciated