More American Graffiti

The film, set over the course of four consecutive New Year's Eves from 1964 to 1967, depicts scenes from each of these years, intertwined with one another as though events happen simultaneously. The audience is protected from confusion by the use of a distinct cinematic style for each section. For example, the 1966 sequences echo the movie of Woodstock using split screens and multiple angles of the same event simultaneously on screen, the 1965 sequences (set in Vietnam) shot hand-held on grainy super 16 mm film designed to resemble war reporters' footage. The film attempts to memorialize the 1960s with sequences that recreate the sense and style of those days with references to Haight-Ashbury, the campus peace movement, the beginnings of the modern woman's liberation movement and the accompanying social revolt. One character burned his draft card, showing a younger audience what so many Americans had done on the television news ten years before the movie's release. Other characters are shown frantically disposing of their marijuana before a traffic stop as a police officer pulls them over, and another scene shows the police brutality with billy clubs during an anti-Vietnam protest.
The listed fates of the main characters at the ending sequence of American Graffiti were updated again at the end of this sequel. In More American Graffiti, John Milner was revealed to have been killed by a drunk driver in December 1964, with the ending scene of the movie driving his trademark yellow Deuce at night on a lonely, hilly highway toward another vehicle's headlights. After disappearing over a small hill, neither his taillights nor the approaching car's headlights are seen again, hinting that the fatal crash occurred there. Set on New Year's Eve 1964, it is never actually shown that his tragic end comes after his racing win on the last day of the year, very probably instead into the first few moments of 1965, given that the 1967 segment was just barely into 1968. The anniversary of John's death is mentioned in both the 1965 and 1966 sequences. Terry "The Toad" Fields' classification as "missing in action" faked his own death being there was no body, he wouldn't be classified as killed in action and as he says he is going to Europe meaning he most likely won't return to America. Terry is believed to be dead by his superiors in 1965 and by his friends â Debbie in 1966 and Steve and Laurie in 1967. Joe Young (the leader of "The Pharaohs"), Toad's war partner, vividly meets his death with a sniper's bullet to the chest in one scene after having promised to make Terry a Pharaoh once they get back from Vietnam.
The relationship of Steve and Laurie is strained by Laurie's insistence that she start her own career, though Steve forbids it saying he wants her to be a mom to their young twins. Free-spirited Debbie "Deb" Dunham has turned from Old Harper to marijuana and has given up her platinum blonde persona for a hippie/groupie one in a long, strange trip that ends with her performing with a country-and-western music group. Wolfman Jack briefly reprised his role, but in voice only. The drag racing scenes for More American Graffiti were filmed at the Fremont Raceway, later Baylands Raceway Park (now the site of automobile dealerships), in Fremont, California.

Question: Whose voice only is heard in "More American Graffiti"?
Answer: Wolfman Jack