Okay, so I just spoke to Jason Ingram from ShoNuff Customs (the guy who owns the truck that Bill tuned for the movie) today. Yes, Bill was right. It IS in the background during the racing scene.
As it turns out, the shipping company carrying the truck arrived, literally, a day late for the two scenes that were supposed to have the truck in them.
Jason said that he's spoken with the producers, and the truck WILL be in the bonus features on the DVD.
The truck might also be featured in a magazine. As soon as I know the details, I'll let you know!
