If you login to your account in the Control Panel, you can go to Code Generator > Standard Search Form. The third option on this page is for the country selection and then postal code entry form. If a site visitor selects a country for which we do not support postal code search, the postal code box will be disabled and the results will display all dealers within that country. Click the Get Code button and copy/paste this code into your web page.
Additionally, you can also choose to only show countries where you have locations by going to Setup Options and checking the checkbox for Only show countries that site uses in search. The default is to show all countries in the world in the country dropdown list. Checking this box will cause the list to show only countries where you have dealers.