A used transmission refers to transmission that has been in a car for a particular number of miles. The transmission has been dismounted from the car and is either being sold online or is now featured in a junkyard.
With a “used transmission”, parts of it, or the transmission as a whole, are sold off as older second-hand transmissions as spares. Online stores and junk yards store used transmissions from discontinued models. Sometimes referred to as a salvaged transmission.
Such transmissions carry a 30 day warranty, at most, and in some instances they are not under any warranty at all. In most instances, used transmissions are found to have weak internal parts which may lead to a variety of transmission problems.