1997 Thunderbird Coil question

I have a bad coil in my t-bird. Is it easier to buy the individual coil? Or the whole coil pack. And if I buy the individual one....how do I know which coil is bad? And what auto prts store can read the check engine code.

AutoZone for one. I think most of the big chain stores must read them by now. It helps them sell parts! Reading the codes might help you find which coil is the problem. OBD-II codes: http://www.obd-codes.com/trouble_codes/ford/