Dana Spicer's convertible tag axles offer improved fuel efficiency, reduced vehicle weight and lower OEM installation costs, while enabling easy conversion from a 6x2 arrangement into a 6x4 configuration. There are also Spicer conversion kits which provide the option of converting existing 6x4 vehicles into a 6x2 configuration. Fuel economy improvements, estimated to be up to 3 percent depending on application variables, have been achieved primarily by decreasing mechanical drivetrain loss and through a total weight reduction.