To install a Gear Vendors overdive, remove the vehicle's transmission extension housing, install the overdrive, and secure it with eight bolts. Take the yoke included with the overdrive to a drive shaft shop, and have the shop shorten it to the size given in the instructions.
Plug the electrical wires back in after you install the overdrive, and fill the overdrive with the lube recommended in the instructions. On passenger cars and vehicles of similar sizes, shorten the studs on the upper rear case. Ensure the transmission crossmember is out, and move the transmission up until it connects with the overdrive. For average driving purposes, replace the fluid within the overdrive every 5,000 miles.
Installing a Gear Vendors overdrive enables the driver to take advantage of such things as automatic engagement, including lights that indicate this, and disengagement, auto lockout when the vehicle is in four-wheel drive mode, manual override, double overdrive cancelling and automatic converter control for lockup converter shifts. The company's overdrive also comes equipped with a shift counter that lets the driver know how much he's actually using the overdrive, a display that indicates when the overdrive is troubleshooting, and the ability to communicate with the vehicle's computer through a digital ratio buffer.