What is my seal called?

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.

I can't find any posts that talk about a crush sleeve on any 7 1/4 on this site.

Do you have a 1971 factory Plymouth service manual for your car? That will be the best money you will ever spend on your car and the CDs are on eBay pretty reasonable.