Err...actually the 757s were modified for the ZB operation to allow extra legroom sales at the front of the aircraft. They used to be in charter config when they were 235 config, then 2 of them got changed to 213 config for ZB before they all went back to 235 and then the decision was made to make them ZB-able again by taking out a row and re-spacing the first 4 rows if memory serves correctly?