20th Century Boys In a session that lasted from 3 p.m. until 1:30 a.m. on December 3, 1972, in Tokyo, Japan’s Toshiba Recording Studios, 20th Century Boy was recorded. When T. Rex arrived back in the country after their tour, they recorded backing vocals, hand claps, an acoustic guitar, and saxophones there. The song’s fade-out on the single version is three minutes and 39 seconds, however the multi-track master shows that the jamming portion of the song lasted for almost exactly three minutes. The Bump ‘n’ Grind collection contains a rough mix of the full-length version.