[RICK LAKE]

JCoop Ray was the fluid silver looking from the rearend or trans? Is there a magnetic drain plug on both? If you have a bearing going bad, new fluid will stop the noise for a few miles, maybe 25-50. Then the noise will start to return. I know the 460 makes big low end torque, if you are lugging the motor you will start the drive train to have pulsing that comes from the motor lugging. What is happening is a slapping of the gears back and forward caused by lugging. this pounds the crap out of the bearings.
I don't know how hard you are on the car but if you are running a TKO 500 trans and the motor has a little work done to it, you are over the torque rating on a 500. I would teel you to jack up the car and get a mechanic stefascope and listen for noises in the drive train. If you hear a groining or grinding in the trans or rearend that doesn't sound normal, it is better to repair it now that break down on a trip or have a failure at highway speeds. Silver fluid in either part of the drive train is not good with only 6 k miles on it unless hard driving. There have been alot of problem with bearings coming from over seas that are NOT up to spec and laminate splits in a couple of thousand miles. You can hide the noise for a short time. Rick L.