I have a '76 Hobie 16 and I noticed one of the clips on the mast is missing a rivet, however I can't identify this part in any of the part guides. I thought it might be a jib halyard clip but it doesn't look anything like the one Murray's is selling (
http://www.murrays.com/07-1140.html). It's also rivetted 90* off. It has a curve to sit horizontal across the mast so I don't believe it to be a part someone just randomly added to the mast. Any ideas what it is and where I can replace it?
Here's some pics:

