The tires are the same size, but the rims are not interchangeable. I think T-bird wheels(year?) are. Most yards will be able to tell you the interchange possibilities.
5 on 4.25 is what a mark 8 comes with a mark 7 has 5 on 4.5 like a mustang. rims that will interchange are from nm12 tbirds, marks courgers, and the new tbird and ls and jags, as well as some other front wheel drive cars.