Mario,
POSTMASTERMC beat me to it. As far as I know, there were no diaphragms on any of the RF-16's, no matter which of the original three railroads who owned them(B&O, NYC, Pennsy) you are talking about. A while back, I was researching photos and info to have sharks custom painted into the Monongahela Ry paint scheme and I was unable to find any evidence anywhere of diaphragms. It wasn't that easy even finding photos of the ends of the A or B units. Here is a photo of a Monongahela B unit shortly after acquiring it from the NYC.
Nick