...... hehe, sorry.
Likely the reason it's jammed in there is that the drive has come apart and is wedged on the back side of the ring gear. Get some help here and put a pry between the mounting surface and the starter and try to turn the crank by putting a socket on the front of the crank. You also may need to pull the inspection cover off from the bottom of the bellhousing and use the teeth to move the flywheel. This is a bitch but it can be removed with patience.
Just FYI, pulling the trans will not nessessarily be a solution either. The bellhousing won't come loose from the block until the trans is out of the bellhousing, the clutch is removed from the flywheel, and the flywheel is removed, all from the inspection cover underneath and through the center hole in the back of the bellhousing. This is because of the thin plate between the block and the bellhousing. This plate is between the starter and the bellhousing. If it comes to that, the starter, bellhousing, the flywheel and that plate will all have to come out together.
Hal
Love hard, drive fast, wear your seat belt.
PS, thats's my 'bird...... My Mustang is too ugly to take pictures of yet........*G*.
http://www.teleport.com/~cosa/bird2.jpg