rear end

[chops]

Making a clunk sound on slow turns and when backing up especially when hot but drives fine no noise and smokes them up no prob

 

[topfuel]

The rear end oil needs to be serviced, I had the same noise when hot.

Change it and use a bottle of that special GM additive.
Can't remember what it's called but I'm sure someone here has a part#

 

[49-blues]

You might be talking about the posi additive "Equatorque". Spelling may not be correct.

 

[topfuel]

here, looks like a few different options, take your pick

http://www.turbobuick.com/forums/general-turbo-buick-tech/343302-rear-axle-oil-change.html