13397 - Customer Satisfaction. Certain vehicles were built with a 3.73 rear axle ratio instead of a 3.42 ratio. With the incorrect rear axle, the speedometer and odometer will indicate 9% above the true value and the transmission shift points will be set for a 3.42 ratio. Dealers are to install a new rear axle with a 3.42 ratio. GM will extend the vehicle mileage warranty as appropriate for accrued mileage on sold vehicles
