Newbie, need help with rear diff fluid change.

Hi guys, new to the grand marquis crown vic scene. I am trying to get some info on what type of gear oil i will need to change the rear diff fluid. I have a 97 grand marquis ls with the handling package n 3.27 rear end. Is there a gasket available for the diff cover or just use rtv?

Since it's most likely an open diff, 80/90 fluid is what you need.
Most people just use RTV, they make paper gaskets that you could put RTV on both sides of but that's a little overkill since RTV itself will do it.