Sometimes it takes a while, but...
One of my good friends in the industry found a contact who worked at the RCA Pavilion, Herb Kircher, who is currently at ABC, WPVI. When I contacted Herb, he came up with three pictures of the tape machines!
[Need a dancing blue banana here!]
Herb is the guy on the left in the first picture. He explained that the center and right machines are the ones for the delay, so although there were three machines (and a fourth in the far background of the third picture), there was only one delay stage.