Also has anyone any thoughts as to WHY a particular car used inward or outward Murphy ends? My own thought is it had to do with the 1910 Safety Appliance Act mandated relationship between the safety appliances on the end of the car and the coupler contour. In the case of these ends being applied to an existing design,using an inward facing rib would preserve the existing relationship at the cost of a small loss of inside length,but saving the need and expense to redesign and retool the bolster/ draft arm area of the underframe.Even a small change in dimension in these areas could change the stresses involved.
I think you're right, as far as retrofits go, and there was no compelling reason to have a different design for new builds. But then somebody figured out that if the ribs protruded outward the nailers for the lining could be buried in the ribs and the lining better supported by the flat part of the end, and they turned the design around, or so it seems to me.
On further thought... Inward facing ribs on a retrofit end would not reduce the inside length of the car because the corrugations are only 2" - 2 1/2" deep. This replaces 3" end framing and 3/4" (actually 13/16") of car siding, so the retrofitted car would actually grow inside. Meanwhile, in the days of MCB couplers with their 9 1/4" striker to pulling face dimension and strikers almost even with the end sheathing, the car ends were much closer together than we are used to seeing with later cars.
Look at where the light is coming from - upper left - you can tell by the shadows of the ladder rungs. That means the ribs on the end are convex toward the coupler (protruding out of the car), since the shadow is on the bottom of each rib, not the top, as would be the case if they were indented into the end.
