Just about any sealed connector (Deutsh, WeatherPack, etc) that will fit should work, such as the one linked in post 1 above. Many auto parts stores here in the Midwest stock parts to make up connectors as well but are greatly more expensive than ordering them from somewhere. My local NAPA store will even sell me one with wire pigtails in place to splice onto existing wires...for about $30 each.
Mouser, Del City, TE.com, Eastern Beaver and others sell them at reasonable costs. eastern Beaver has a nice tutorial on using the crimper he sells as well.