I believe you have to pull the fender well out to access the antenna. Do you have the premium system? If so you will have to route the antenna lead through the kick panel & behind the glove box.
Mine quit almost 4 years ago but I never repaced it because I never listen to the radio. I have a CD in at all times.
The radio stations in Knasas City suck to say the least. Between worthless trafic reports, commerecials & the stupid blathering DJ's you get 2-3 songs in a half hour if you are lucky.