In the days before automatic transmissions were common, especially in the 1950s, many rear-wheel drive American cars were available with an overdrive option. With substantial improvements developed in Muncie, Indiana, by William B. Barnes for production by its Warner Gear Division, BorgWarner provided the box that was factory-installed between the transmission and a foreshortened driveshaft. Since the overdrive function, if enabled, could be shifted by simply easing up on the accelerator without depressing the clutch pedal, the action was much like a semi-automatic. Also, an electrically operated solenoid would deactivate the unit via a switch under the accelerator pedal providing the equivalent of the kickdown of the automatic. A knob connected to a bowden cable, similar to some emergency brake applications, was also provided to lock out the unit mechanically. Using overdrive with the main 3-speed transmission in 2nd gear was similar in ratio to 3rd gear, and with the main transmission in 3rd, the overall ratio was fractional (i.e., "true overdrive"). This was important in reducing wear, tear, noise, and difficulty in control.