1. Seriously shake the transmission.
2. Using a big flathead screwdriver and a hammer, punch the area where the transmission meets and engine.
3. Use 2 floorjacks. Work with them. Try lifting up transmission and lower the engine and vice versal.
4. Call and bring another helper or 2.
One of the reasons why it's stuck is because there are 2 alignment pins that maybe little rusted / oxidized. Spray them with wd-40 as well.