So to make sure I am not confused, for my 91, get 94-95 spindles and have the front track be a little (3mm?) wider? How do I ID the right spindles if they are not on the car? Do you have a part number? Then, use the PBR set up I have if the rotors and calipers are good? See here for my spare parts.
http://www.stangnet.com/mustang-forums/threads/name-that-brake-part-set.863855/#post-8702003
@stykthyn is it really obvious what and how much needs clearanced on the spindle, and is it for the caliper or rotor?
Spindles do have part numbers. Pretty easy if you know Ford's typical engineering scheme with part numbers.
The 94-95 spindles will start with an F4 or an F5. 1994 is F4 and 1995 is F5. Unsure what the change is, but there are two part numbers. I actually have 1 of each on my car.
The 1996 spindles will have an F6 part number (meaning 1996). There might be some later year changers, but the part number will refer to the year. For instance F8 would be 1998.
Dust shields are all the same 94-04 for all models, and doesn't matter if ABS or no ABS
Visually, a picture is worth all that mumbo jumbo i just said
Fitting the 99+ GT PBR's is easy. Clamp the spindle in a vise and lower the caliper down and attempt to bolt it on. You'll see where the pistons hit. Clearance this with a dremel until the pistons clear and are free to move in and out without interferance.