It is usually possible for an amateur mechanic to install a new transmission in a car or truck with the proper tools. However, some vehicles use transaxles or other specialized transmission designs that may be more difficult to install than standard transmissions.
Transmission replacement is considered one of the harder jobs for an amateur mechanic, but replacing a car's transmission with a ready new unit is significantly easier and less time-consuming than rebuilding a transmission. The procedure requires a floor jack, screwdriver, pliers and a drip pan, as well as a supply of transmission fluid for lubricating the new transmission after the installation. Removing the old transmission also requires disconnecting the battery and disconnecting wiring and removing other components, such as the starter. Disconnect the battery for safety, and apply electrical tape to electrical leads to protect them while they are disconnected.
The precise procedure for dismounting and remounting the transmission depends on the design of the car in question. Front-engine, rear-wheel drive models usually use a standard transmission and driveshaft configuration that is located behind the engine and is relatively easy to remove and install. Four-wheel drive and front-wheel drive models use more complex systems that are sometimes tightly packaged with the engine, making them more difficult to remove or replace.