OK, speaking as a park ranger (Oh, look! It's a little girl in a big truck!), avoid any Dodge that isn't a diesel like the plague. There is a reason the State of Maine no longer buys Dodges for the Department of Conservation...

Personally, I like GMC/Chevy (they're the same truck, trust me). I drove my little S-10 for 12 years and now my youngest brother-in-law has it. The best park truck I've driven was a 1995 GMC Sierra 2500. Not the world's greatest gas mileage, but a very dependable truck. I used it for five years and in two different parks, then it "aged out" of the fleet and went to auction. Someone got a good deal when they bought that truck. In the five years after that, we've gone through three Dodges, one of which I referred to as the Truck of Doom and kept telling the higher ups that it was an unsafe vehicle. No one listened and then it cuaght fire in the parking lot and burned to a shell, nearly doing in the guy who was plowing woth it. He got out just as it went "Whoosh!"