Websites like Powertrain Direct offer new transmissions for a wide range of vehicle makes and models, and buyers can also contact local car dealerships and service centers to find out if they stock new transmissions. New transmissions are generally easier to find for newer vehicles.
Vehicle manufacturers often use similar components for several years, and many use similar parts on different vehicle models. This, combined with the fact that automatic transmissions frequently wear out over time, means that major car manufacturers often keep producing new transmissions even after the vehicle is no longer being produced.
New transmissions are often expensive, and third-party transmissions are relatively rare. As a result, many buyers turn to used transmissions. Certified rebuilt transmissions are those that have been professionally serviced, and they generally pass an inspection before being sold. While they might not offer the reliability of new transmissions, they often come with a short warranty to cover premature failure.
Vehicle warranties sometimes cover transmission problems, although these warranties often expire before most automatic transmissions fail. Replacing a transmission is expensive, but much of this expense is due to the labor required. Drivers who feel comfortable handling heavy items and who have someone who can offer advice might be able to save money by performing the work themselves.