Just got a 99 TA and there is an excessive amount of noise coming from the rear end, you can hear it inside the car enough where its annoying. It does not seem to be the brakes at all. I pulled the rear cover off and it appears that the fluid was low just by looking at the stain lines under the cover. I refilled and added the posi additive, and it still makes alot of noise.
The '95 TA I have is very quite and both are convertibles so thats not the difference I'm hearing.
I'm afraid that the person before may have driven it too much with low fluid and messed up the axle bearings/races??

 

that would be my guess. is it a whine, or more of a growl? low fluid=friction=heat=bye bye rear.....(im sure you knew that though)

 

It sounds kind of like a growl, like tire road noise but alot louder.