2013 6 speed, 4x4, 3.55 rear, pedal commander, 275/65/20 , no speedo recalibrate.Truck runs shifts tows fine 8 speed would be great to have. The charger and challenger that we have have the 8 speed.But only have 40k miles on the truck plan on keeping it for a another 4 or 5 yrs.Not worth the $$$...