I've had a dozen or so racks in my two cars. TRW and Ford both made the power racks. One has the central rack piece made in two parts, one is a one piece casting. I think the valve area is different.
As far as I know, they will all interchange one way or another.
However, I have found two types of stub shafts, one with a flat to index and one that is all round, with a master spline to use for alignment. They have different mating pieces on the lower part of the rag joint. As long as you have the correct spline type fitting on the rag joint it works. Either type part will fit on the rag joint assembly.
The hose fittings have also varied, but most replacement racks come with adapters.
T bird and related racks are the same, but the inner tie rod part is longer, and may not thread far enough into the outer tie rod to allow setting the toe in. It can be fixed by cutting off some of the tie rod, or by bottom tapping the outer tie rod threads.
I have changed or fit a rack with all of the above to one of my cars at one time or another. Finally went manual on the 82!