call your local ford dealer. Ask for theyre parts department, they would be able to help you no problem and let you know what may be involved. I work in a body shop, I own a GT and cannot honestly say I have ever taken a front bumper off our body style
stang. From experience it wouldnt take more than an hour. But thats easy for me to say. If you have a lift it would be much easier. Depending on the brackets you are talking about, they are probably not attatched to the bumper and can be bought seperate.
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2004 Mustang GT---
BBK Shortie headers, Bassani o/r X pipe, SLP L/M cat back, Professional Products 75mm t/b and plenum, BBK CAI, SCT full custom tune, 3.73 Ford Racing Gears, Steeda triax short throw, BBK lowering springs, 17x9 17x10 corbra 10th ann (lipped) knock offs, Mach one grill delete and front lip, and some other little stuff.