yep the only thing similar is the diff, and they are not interchangeable, they are both 8.8's but obviously meant for different style suspensions, so you are out of luck there.
the thunderbird rear that would be useful is from an 87-88 thunderbird turbo coupe, especially if you can get one complete with the disc brakes. 5-spd TC's came stock with 3.55 gears and the auto cars had 3.73's.
if you want to use the ring and pinion and the trac-loc from that 93 rearend you can. only thing you have to do to the tbird trac-loc is get different side gears. they are machined for the irs axles. other than that the guts are swappable