rubber cover on shaft? or something

My apologies for not knowing what most things are called but I'm trying. Heard a pop on the highway and then noise that increased in volume with speed of the car. the rubber cover on the shaft was ripped and flapping around causing the noise. Part of it pulled off easily by hand, (noise lessoned considerably but did not totally disappear. also noticed a few loose rings (thin metal). What part am I dealing with and what else should be checked. The car still drove great, 63 valiant /6. I have had good luck using rockauto for parts any other suggestions. Thanks.