GM 4th Gear Overdrive-Lockout
* The Overdrive-Lockout is designed for vehicle applications that are extremely over loaded on a daily basis and for durability purposes are best kept out of overdrive. The lockout switch when activated will disallow overdrive even when the shift selector is placed in the overdrive position. This insures the vehicle will not be operated in overdrive even when multiple drivers use it. With the switch in the off position (OD Normal) complete normal operation is resumed.* Will service 4L60-E and 4L80-E transmissions Thru 1999.