Diff Cover... To Rtv Or Not Rtv... That Is The Question

I actually bought a Ford Motorsports reusable rubber gasket, no idea if they even make them any longer.


The reusable ones for the valve cover gaskets are awesome. First few times I ever did valve cover gaskets, I just used cork and a little RTV. What a PITA. When I got the reusable ones, it made life so much more easy
 
So mad... used black rtv. Got the rear end installed. Realized I forgot to tighten the bolt on the carrier pin.... guess the first time was for fun.

Anyone know what the full plug on the rear is? Allen? Torx?