like lets say i am looking on ebay for a transmission what would i be looking for are all ford manual transmissions interchangable ? Can somone please help me?

I have a 2004 Ford Taurus, only 45k miles, real nice condition. I want to get rid of it but dont seem to know how. I am looking for a place where i can list or sell the car for the closest to my asking price.
Things I've Tried:
-Local Community Paper
-Ebay

Can't seem to get autotrader.com to post my pics.
Any info at all is greatly appreciated!