1999-2004 are all the new-edge sn95 body style, so all body parts from any of those years will bolt right onto your 02. There are some cosmetic differences on some parts though, such as the 99-01 having a flat hood without the scoop, and the 02-04 having the flat hood with a scoop on top (if they are GT or V6 pony package models). The wings are also different on a couple of those years (think it was 99-01, then 02-04 on those as well), but again, everything will fit just fine.
Most junkyards, and all dealerships have a parts interchange program that they can use to help you find your parts if you're uncertain.
The best part about these mustangs is there are several that will be interchangeable so finding parts should be very easy. I believe you are dealing with 2000-2004. Any dealership will have the answer, but I would just check with a local junk yard or on ebay. Most Ebay sellers list what model cars and years the parts will work with and that has been the best source as far as price that I have found for mustangs.