I have a 1997 Thunderbird and it doesn't pull at all to either side when I brake. Of course, it has 156,000 miles on the odometer and I've replaced ALL the brake parts (at all 4 wheels) as well as ALL the front suspension components within the last year! It had a number of brake/suspension problems when I bought it, but it still braked without pulling to either side even with the original parts that were on it. I even have cheapo strut-rod bushings on the car right now that I'm getting ready to replace with Ford OE parts, but it still brakes straight & true. I guess my point is not ALL T-Birds/Cougars pull to the side when braking!Wow, that's a freaking rip off if I've seen one and I've gotten gipped a couple times. This problem seems to be inherent to T-birds and Cougars (pulling to the right). Many people have that problem. I do too! I just haven't gotten around to getting that damn caliper off. I meant to do it tonight but got lazy... Bleh...
I have noticed a small amount of rust on my brake pad, so I think if I sand that off it will help.
Any number of issues could cause your car to pull to the side when braking: worn ball-joints, loose wheel bearings, alignment issues, a sticking brake caliper, loose suspension mounting hardware, etc. You need to check not only the brakes, but the entire front suspension for loose, worn or mis-aligned parts.