NUT, Hex Washer Head #12-24, locking, zinc, serrated washer, replacement style, original had a plain spin washer, This nut is used to secure the fuel cap security cable or pop open fuel cap bolt on the inside of the trunk to the back of the taillight panel
NPD Part Number : 380331-S8 Manufacturer Reference #'s: 380331-S8
1965-1970 MUSTANG STANDARD AND POP OPEN FUEL CAPS
WARNING: This product can expose you to chemicals including lead and DEHP, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.