Those C-22 tubes
I personally would not bother with trying to replace the turnbuckle covers. They do not serve any useful function that tape around the turnbuckle cotter pins will provide. Nevertheless, you might get them from Catalina Direct or maybe even Catalina itself. However, some people use a long thin wall PVC tube of several feet around the forward lowers providing a roller function for the jib sheet. You could also do this for the upper shrouds if you have a furler and don't want the jib sheets to chafe against the upper shrouds when the furler is furled. Unfortunately, I can't provide any good diameter for these, but I'll check my boat tomorrow. As you have a 76 boat, it is possible you have 3/32 inch lowers while the uppers and stays are 1/8 inch. The 3/32 inch lowers are 1/8 inch since at least from 1980 although probably earlier than that.
