I have Permatex Ultra Black.

 

There is an old thread around here SOMEWHERE with a picture of the RTV that the Ford dealer sells specifically for this - it says Motorcraft on it, it ain't cheap, but I believe it's just a relabeled Permatex product. The thread also details the exact right way to prep and use it.

I had my rear done last fall at the quick lube, and they used a gasket. It hasn't leaked a drop. They used BG lube and modifier.

 

Where do you get a gasket for the 9.75. My chevy and dodge rear ends both use gaskets.

 

i like the gray

 

I dunno about the 9.75, but Autozone had the gasket for my 8.8, it's a Fel-Pro.