What is my seal called?

Part # : 8516N | Line: NAT

Wow that kids was right. Thanks for checking for me. I just watched a video on you tube..."different vehicle", and he was using white out to line everything up and counting threads. I am gonna find out the torque and do it right.
I just need to make sure there is nothing else that needs replaced.
My car sat for 20 years. There only 69k on it. SO the seal must have dried out.