I have a 88 samurai, when i got it it made a noise like change clattering when in motion, i have located the issue and it appears to be a metal ring at the tail shaft of the transmission it is app. half in wide and solid around, i would think this is part of the rear seal but unsure, could someone help me diagnose and offer a resolution,  also this must have been an ongoing issue for some time the way the prior owner descibed it, everything appears to be functioning ok with the tranny but what type of damage should i look for.

i have yet to pull anything apart due to haveing to remove underbelly skid plate and the rainforest type weather we have been getting latley

thanks