I'm about 98% sure the flywheels are different from the truck to the car.
The 2nd link is already posted.
The Mustang one should have the 157 tooth wheel, and the T18 would be the 164 tooth.
Flip the flywheels over so you're looking at the back of them, check the counterweight block cast into them. If they look roughly the same size (amount of material wise) they'll switch right out. If one looks to be about 2x as much material as the original mustang wheel, you're going to need to search around of another flywheel.
'80 was around the changeover year, but the mustang flywheel should have the 28oz counter balance IIRC from my own flywheel predicament.