Ok, *if* it is an AN type fitting, the male part coming out of the sump will look like the piece on the left. You can see the flare on the tubing inside the nut. Normally, a failure is a crack in that formed flair. The good thing is.. it's not suddenly going to fail and dump all your oil on the rear tire. The bad thing is you have to take the fitting apart to inspect it, thereby losing all your oil..
2018-10-30_03-33-13 by Charles Stottlemyer, on Flickr