I installed a Quick Performance 9" housing and Yukon center section in my 57 last summer. I bought a Fel-pro gasket for it. I used Ultra black RTV on both sides of the gasket. Worked great, no leaks. It would probably work without the gasket but I didn't think the housing and carrier mating surfaces were perfect so I felt like it was good insurance to use the gasket.
I think I will use a gasket because I was installing the studs into the housing using a stack of washers and the washer on the bottom of the stack spun slightly and put a really minor gouge in the housing. Guess which stud: DEAD CENTER at the bottom. I touched it up lightly with a file to make sure it had no high spots but I can still feel it with my finger nail.