Will a 2000 Ford Mustang transmission Fit in a.

If he little rodents get under the car and use the wiring for breakfast lunch andor dinner then sitting can damage it otherwise it may have been damaged prior. A 99 may work as long as its 'the same type and the electrical will hook up to it. But the electrical could be wired different between the model years. You'll hav eto find that out. Have it scanned for codes and fluid checked first it may be a minor problem with trans in car.