Try Catalina
Call 818-884-7700 and ask for parts. If they won't supply it, you should ask for technical support and David will gladly send you a drawing, or give you the dimensions so you can make one, or have it made locally. These are often made of vinyl coated stainless wire, with a thimble at each end and secured with a Nicopress crimp fitting. You can actually buy all the parts and make this in the store at West Marine (at least you can in New Bedford, MA). For my C-36 I used Kev-cord, a super-low stretch, super high-strength cord with a dacron outer braid and Kevlar core; I seized the ends onto stainless thimbles. jv