This F-4E was active with the Thunderbirds from 1969-1973 and flew as the slot a/c, #4. The slot a/c flies behind and slightly below the lead F-4E. As a result, number #4 vertical fin and rudder are in the exhaust of #1, causing the dark staining. It was not cleaned off during the season to show how close together the a/c flew. After the Thunderbirds switched to the T-38 in 1974 this a/c was assigned to the USAF Flight Test Center at Edwards AFB. Retired in 1991 and eventually scrapped.