@rdunniii posted:Where when? The Superliners ran with F40s from the day they were delivered.
Right, an F40 was required, but SDP40Fs did run in Superliner consists. As I understand it, the SDP40Fs that weren’t scrapped or sent to EMD to be rebuilt into F40PHRs were given the HEP pass-through treatment. Last SDP40F to leave the roster according to the Wikipedia article was in 1987.
Here’s a couple photos I found. First photo by Craig Walter, second is by Roger Puta (public domain).