I never use RTV on any gaskets, I uses gasket sealer, such as Permatex Aviation. But you can do what you want....
Permatex non-hardening gasket sealer. When you refer to "banjo" do you mean this type of rear end? 1932-48 Ford
Three Bond 1104 is pretty good too. Light grey color. Sent from my iPhone using The H.A.M.B. mobile app