Well I'll be a monkey's uncle. From: "The Concert File" by Dave Lewis & Simon Pallett, "Rehersal, May 1973. A soundboard recording exists from a 1973 soundcheck (where the band plays Elvis and obscure Johnny Kidd & the Pirates numbers) which is often erroneously cited as having been taped prior to the Jul. 6th Chicago date. From the quality of Plant's vocals (which were in poor shape at the beginning of the second leg of the U.S. Tour) it's evident it's from the first leg of the tour, possibly from the afternoon prior to the May 4 show." Conjecture. Speculation on behalf of Dave Lewis?