I have a 1990 Toyota pickup, and I noticed when I got stuck in some sand that only the passenger side back tire spins, while the driver's side does not. Any ideas why?
Your truck is most likely equipped with an open differential. This is a normal condition. A few vehicles are equipped with what is called Posi-Traction, Sure-grip or locking differential. These differentials are equipped with internal clutches that spin both rear tires when moving in a straight line. When going around a turn the clutches release allowing the tires to turn at different speeds.