The steering racks used on stock, non-sport 1983-88 Cougars have a constant 20:1 ratio, and that's why you have to constantly turn the steering wheel while driving. They are approximately 2-3/4 turns, lock to lock, and are boosted quite a bit for low effort. If you do not like the numbing feel given from this rack or just want a better rack for more aggressive driving, then upgrading to a high-effort 15:1 (technically a 14.7:1) rack is a must. In fact, it's probably the single biggest front-end improvement you can make, requiring just over 2 turns lock to lock.
The 15:1 steering rack can be found in Cougar XR7 (1983-88), Thunderbird Sport V8 (1987-88), 5.0 Mustangs (1987-93), and all Thunderbird Turbo Coupes (1983-88). Once it's broken in, you'll notice a huge improvement in steering (and you'll find yourself going out of your way to find a really twisty road). The difference between the two racks is absolutely amazing. If your rack is shot, then the 15:1 rack should be considered for a replacement. For those of you who may have carpal tunnel syndrome or arthritis, then it's our experience that you should stick with the stock 20:1 rack for increased steering assist.
You must also remember that if you're upgrading from a 20:1 to 15:1 rack, you should also consider upgrading your power steering pump to match. There is a difference between the pumps, at least on paper. In reality, plenty of people have simply reused their old pumps without much issue. If there was some sort of serious problem then we'd definitely report it here; as of right now we're not aware of issues.
If you are drag racing your car or want to eliminate power steering in your car, you can use a Mustang-oriented manual rack, such as those made by Flaming River. Occasionally you will find manual stock Mustang racks as well.
One thing to remember is that steering racks are chassis-specific. You cannot easily use a 1994-up Mustang (SN95/Fox 4) rack on an earlier Fox chassis car without modifying the inner tie rods; It's much simpler to use a Fox rack with a Fox car.