Yeah I read that too somewhere, that they are sealed on via factory with sealant type gasket. The previous owner had used a cork gasket and it was leaking out a number of bolt hole areas and the rear end.

When I put the Permatex gasket maker on there I put it in that groove and circled the bolt holes.

So far two days of driving and no leaks. As far as I'm concerned, I'm better off now than I was when I started.