The transmission system of a car is one of its vital and most expensive parts, which is why it's disheartening to learn that your transmission has failed. Fortunately, a failed transmission doesn't mean that you have to junk your car; you can fix the issue via any of these three routes:
Buy a Used Transmission
You can get a used transmission from a junked car as long as it is still in good condition. You can buy such used transmissions from online vendors that sell car parts, junkyards or from local auto mechanic shops. Note that the auto mechanics rarely warranty transmissions they don't supply on their own; therefore, you may not get a warranty on the repair if you buy the part from a junkyard or online vendor. It's good to know why the car from which the transmission was removed was junked in the first place to ensure that the transmission you wish to reuse is really reusable.
Rebuild the Transmission
Another viable option is to rebuild the failed transmission. This involves disassembling the transmission so that it can be inspected for damaged parts; the damaged parts are then replaced. During the rebuilding process, the mechanic will not replace any part that has not been worn out beyond the manufacturer's specified tolerance limits. This means a rebuilt transmission may just be acceptable, but not as good as new.
Also, the quality of the auto mechanic shop rebuilding the transmission matters because it is their expertise and experience that helps them determine which parts to replace and which ones to reuse. This means a transmission rebuilt by a so-so mechanic may not withstand the test of time.
Buy a Remanufactured Transmission
Lastly, you may also replace the failed transmission with a remanufactured one. During the remanufacturing process, the mechanics take a used transmission and cleans, inspects it and restores it to its factory standards. It is almost like rebuilding a transmission, but the quality of work here is higher and the resulting product will be as good as new. You can buy a remanufactured transmission from your local shop, a dealer, online or even directly from the OEM (original equipment manufacturer). All of these options have their pros and cons so you need to evaluate them carefully before picking the best one for your case.
If you have a failed transmission, talk to your mechanic to help you know more about the above options (plus any other viable option). Take your mechanic's advise under consideration when choosing the route to follow.