Hey -- I just refurbed mine. I took them all apart, had them bead blasted and powder coated, then used the rebuild kit from Pelican to change all the rubber. Not a hard job at all, except for misplacing this part. Follow Dwayne's writeup and you should be fine:
Rear Caliper Refurbish ('84)
It turns out 928 Int'l had a couple of those clips, so all is well. I will say that I think the clip is on upside down in the picture above. When those little tabs are facing down, the clip serves to keep tension on the cotter pins and therefore keep them in place.