Here are the photos that were requested.
Note. Yesterday's reply, "G" mentioned a different diaphram. In the MTH parts breakdown, they did show a 4 rib for the B & O and ATSF. The 2 rib was for the PRR & C&NW. MTH part # FL-0000026
This is a PRR and must have the wrong rib diaphragm.
Look at my photos. One of them shows a curve at 072. Note the interaction.