What is this part called?

4spdragtop said
If the dust shield is toast, take a good look at original balancer and make sure it's good. 50 yr old part

Thanks 4spd. The original balancer is definitely NOT good. That's why I swapped to an aftermarket. Idiot me, thought the dust shield was supposed to transfer over, so I pulled it off and put it on the new balancer.