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Altered the title of the thread to show the specifics By back up wiring clip I'm guessing that your referring to one like what is shown on Jack's sitehttp://www.deadnutson.com/catalog/item/4065497/5384368.htmIf so then we can try to work from there. As rockhouse66 mentioned there is a retainer on the face of the firewall before the connection plugs into the firewall junction