Can someone tell me how to check my rear differentail. The truck is 03 quad cab 4x4 with anti slip rear end. I keep getting hung up on level ground in two wheel drive. I only have one wheel pulling at the rear. I jacked up both sides of the rear of the truck. With one wheel touching the ground the other up on an jack. I can put the truck in gear. and the wheel which up is the only one that turns.