Have you contacted Catalina Yachts customer service and parts department? Go to
their website, scroll to the bottom of the page for contact info. Here's a contact number for parts and technical support .... 727 544-6681.
You can also try contacting any dealer.
The spreader boots jssailem refers to are not the same as the end caps. The boots are a covering to protect the headsail when it rubs against the spreader tips. The caps are part of the spreader tip that secures and guides the shrouds but with minimal sail protection. Besides the boots on the spreader tips, protective patches can be applied to the sail itself.