96 2.2L Cavy transmission....

First of all... bear with me as I am going to give you the information that I received. The car is my fathers girlfriends. The transmission is a 3 speed. Somehow the transmission just up and let go one day. Not while being driven. It drove fine the night before and was parked overnight. The next morning it needed to be moved. After the car was started it was put into gear and there was nothing. Park still holds the car in-place. When you shift to any other gear, there is no noticable"change" of gear. Once you put it into drive or reverse though, if you can manage to push it to get it rolling it will then continue to move and pick-up speed with the accelerator depressed but once you stop the car it is dead in its tracks again. My father and I have already aquired a used transmission from a junkyard. I told him that I would check here first before we proceeded with anything. He already tried changing the fluid and filter but that did nothing. He also tried to let the car "warm-up" for 20 mins at idle, still nothing. If there is anymore information that is needed please ask. I am hoping we can try something else before we absolutely have to replace this transmission. Anyone have any ideas?

TIA,
Jeremy

Anyone got any clues or possible ideas about this?? We are going to be starting on it soon and I am hoping to save what is in there first without having to change it. Thanks!