My '03 enthusiast has a squeak coming from the rear right wheel that at first would come on at random and was very quiet now it's more or less constant and much louder. Took a video to a capture the sound (wait til the very end). I know this really isn't much to go by to diagnose the issue, so if someone could tell me what to check for when I jack the car up I'd appreciate it.

 

You don't mention how many miles are on your Z, or whether there's been any damage to the RR. Your sound clip wouldn't play either, so have you checked for any axial play in the RR wheel bearing?