Clunking driveshaft/tailshaft? Help!
I have a 94 7.3idi dually rwd with an e4od. I’ve been hearing/feeling rapid clunking underneath floor board when driving. Upon inspection my drive shaft has play when pushed up and it needs replacing. However, my question is for from my understanding the tail shaft? Its the part that connects to the driveshaft from the tail shaft housing. It has play/clunks when wiggled up and down. What causes this play, what parts do I need to fix this, and what is involved in repairing? Any help/pointers is very appreciated, thank you!
Attached is the problem part



