Correct me if I'm wrong. There are only 2 models of hydraulic steering pumps manufactured by Ford, the C-II and the C-III. Both are still in production, and these are the only 2 PS pumps I've ever seen used on Ford products.
The C-II pump is what's used on all 3.8L engines, as well as some other vehicles, including some F-series trucks. It's identifiable by it's integral fiberglass fluid reservoir, mounted directly onto the back of the pump. The reservoir is usually yellowish-brown, sometimes black, and has the 1/4 turn, dipstick cap on it. This is the unit you see on the the V6 MN12's, and the Taurus, as well as other vehicles. The C-II pumps have a habit of becoming noisy, and making the whining sound, regardless of how well they're maintained or what mechanical shape they're in. Once they get a few thousand miles on them, they whine.
The C-III pump is the better of the two, IMO. It's smaller than the C-II, and it's readily identified by the absence of any fluid reservoir on the pump itself. Rather, it has a port on the body that allows connection of a remote reservoir, making it useful it cramped spaces, like on the 4.6L V8 MN12's, some F-Series trucks, Focus, and other vehicles where space is limited. I've never heard of this model pump making any "bad" noises, unless it was broken or low on fluid.
EDIT: on the C-II unit, possibly on the C-III, there is an internal valve (forget the correct name of it) that is calibrated to the specific vehicle the pump is used in. I believe it is used to adjust steering effort. This is not to be confused with the external VAPS or EVO actuators found on some units.
Hope this helps!