Don't know if you have a diesel or an Atomic 4, as that year Catalina sold both. But check for a clogged fuel filter. Also check your fuel tank fuel lifting pipe, as it can get clogged at the end where fuel first enters, & so does a lot of crud from an old fuel tank. Usually diesels will either fail to start because they are not getting fuel, or bad compression (hopefully not the case). A 4's on the other hand have a host of added potential ignition problems that can cause failure to start. If you have an A 4 check for a good spark at the end of the spark plug wires. I have a John Deere tractor that wouldn't start recently. After merely replacing the spark plug it started right up. The plug was so gummed up with soot that it couldn't make a good spark. Sometimes its just the little things that cause a problem that we don't expect. If you have a diesel, then plugs are one less thing to worry about. Good luck.