Bella was hesitant to like it at first, worried that it would cost too much money to keep up and that it might be in bad condition, but as soon as she saw it, she knew it was perfect for her.
You guys forgot about the part where Edward decides to be a control-freak and takes a part out of it to prevent her from seeing her best friend... (the one who was still there when Edward abandoned her)
It's described as a 50's-60's faded red/orange truck, bought by Billy Black in the 80's and frequently repaired by both himself and Jacob. Billy didn't want to sell it, but lost his need for it when he became disabled. On Stephenie Meyer's website, it is said that her truck is a 1953 Chevy Pick-up truck.
In the movie, Bella's truck is a 1963 Chevy StepSide C-10 pickup.