I personally just run a small bead and install the cover.

 

Either way should work but I prefer to lay a bead of sealant.

 

I have usually had good luck with a thin bead set it in place hand tight to spread the RTV. Let it set for an hour or so to cure some then torque it down about half way. Then bout half hour later torque to spec. Always worked well for me takes time but no leaks from the diff which are common on a lot of older vehicles.

 

Got it, thanks guys!