I was at the dealer on Friday and looked over the '04s. The only big change I noticed is the literature now claims the Cummins does not need to be plugged in until 20 below! With this change, it appears that the block heater is now a $10 option. Does anyone know what was done to lower the temperature? I plug in at 10*, but occaionally have had to start at 10 below without being able to plug in. If the changes are able to be retrofit into an '03, I might be interested. By the way, even at 10 below, outdoors in the wind overnight, it starts. Just sounds like a second gen for awhile . 
