Instructables user 5hockwave2 shows you how to open the case for your remote, and add some wire—any thin wire should do—with a little solder to the existing antenna.

Your classic car probably has a lot of features you love, but remote keyless entry is probably not one of them. Fortunately, there are ways to add it.

Remote keyless entry systems can vary in terms of features and connections. Hence you will need a manual with programming instructions for your specific car brand and type of remote keyless system.