Task: Question Answering
Input (English): Passage: New York Dolls is the debut album by the American hard rock band New York Dolls. It was released on July 27, 1973, by Mercury Records.
In the years leading up to the album, the New York Dolls had developed a local fanbase by playing regularly in lower Manhattan after forming in 1971. However, most music producers and record companies were reluctant to work with them because of their vulgarity and onstage fashion; the group later appeared in exaggerated drag on the album cover for shock value.
After signing a contract with Mercury, the New York Dolls recorded their first album at The Record Plant in New York City with producer Todd Rundgren, who was known for his sophisticated pop tastes and held a lukewarm opinion of the band. Despite stories of conflicts during the recording sessions, lead singer David Johansen and guitarist Sylvain Sylvain later said Rundgren successfully captured how the band sounded live. Their music on the album incorporated carefree rock and roll, Brill Building pop influences, and campy sensibilities, while Johansen's colloquial and ambiguous lyrics explored themes of urban youth, teen alienation, adolescent romance, and authenticity.
New York Dolls was met with widespread critical acclaim but sold poorly and polarized listeners. The band proved difficult to market outside their native New York and developed a reputation for rock-star excesses while touring the United States in support of the album. Despite its commercial failure, New York Dolls was an influential precursor to the 1970s punk rock movement and has since been named in various publications as one of the best debut records in rock music and one of the greatest albums of all time. 
Question: What are the last name of the two band members who said Rundgren successfully captured how the band sounded live?
Output (English): Sylvain.