I have a 1994 LT1 Camaro with 3.73 posi-traction. Just noticed the other day coming off the highway I can hear whining noise louder than normal. I changed my gears about 5 years ago with no problems. You can't hear this noise when I am acceleration on the gas only when I let go of the gas and the car is cruising. Would this be my pinion bearing?

 

Get under there and give it a shake. If it's loose enough to have any movement, its probably already damaged. If it seems tight you might have to take off the cover and take a look inside.