Wheel bearings a hummin' ...sealed, or not?

I drive a 98 GT Conv w/ about 88,xxx miles and was wondering about the types of wheel bearings on it. I've heard on car talk that '94+ Stangs switched to sealed front bearings and I'm assuming the rears are not. I've called the local dealership to ask about repacking my wheel bearings and they quoted about $115 for repacking all four. Now, you can't repack sealed bearings so I'm not sure which information to go by in telling me what types of bearings my car has.

Also, is repacking (no gay jokes ) something I can do in the parking lot of my apartment complex on a warm January afternoon in Orlando with some simple tools?

Difficult to pin-point ....

since the cabin is already noisy due to it being a covertible. The hum isn't very loud, just louder than it used to be a few months ago.