General discussion for the Fox 5.0 Liter Mustang from Ford.
stangnet.com
I have this answer for you though.
Find a Pull-A-Part Yard in your area. Take jumper wire and something that will provide you 12v dc in there to test out some of the seat tracks before you buy one.
If you are not 100% on the motorized track. Get yourself a passenger side seat track which should be a manual. I have a 95 convertible and did this exact thing in mine. I was not going to pay $300 for parts for a motorized seat. It is not hard to swap the track over and you'll never have to worry about it being stuck again.