Right, Doug. The 155 PS rail came from PRR. Penn Central didn't buy any after they adopted 132 RE as the heavy section. The only other (non-PRR) property that I know used 152 and 155 PS rail was the Bessemer and Lake Erie, though some of it might have been used on other US Steel roads. Any 155 lb rail on Erie Lackawanna track was laid by Conrail after April 1, 1976. 152 and 155 PS rail had a problem, in that it was actually heavy and rigid. If a low joint developed due to rail end batter or poor ties or ballast, with lighter rail sections you could raise the joint and tamp it, and the rail would sort of straighten up (one hoped.) With 155 lb rail, if you jacked the joint, all of both rails would come up and the rail never wanted to bend back to its proper shape.
I saw a lot of confusion on Conrail and successors over 136 lb rail. There were several different 136 lb sections on the Lehigh 'Valley, dating back to the 1930's. There are several different 136 lb sections based on AREMA recommendations that also fit 132 RE joint bars. 132 RE, 136 RE and 136-10 rails have the same fishing dimensions (fishing refers to the points of contact between the bars and the rail). 136-10 is 136 RE with a 10-inch radius crown on the running surface.
136 NYC and the 136 LV sections are all entirely different from the RE family. They caused all sorts of problems with matching rail sections and compromise joints (joints used to join rail of one section to rail with a different section).
By the way, 127 Dudley was a pretty good section for the New York Central, which used it successfully for high speed service on gradual curves. It is a high, thin section (7 inches high) and relatively stiff. The Dudley Modified section improved it mainly by using a wider radius head-web fillet to avoid cracks that led to head-web separations. The 127 DY and DYM head is a bit narrower than some other common sections, so that provides less metal for loss by curve wear. The web is also narrow, and more susceptible to bolt hole cracks. The standard joints in 127 DYM moved the bolt pattern back into the rail by one-half inch, and that reduced the incidence of cracks in the No. 1 bolt hole.
I suspect that the 127 DY rail on the KCS might have been owing to influence by Leonor F. Loree, who was concurrently Chairman of the KCS and President of the D&H in the 1920's and '30's. Even though the D&H didn't use it, as I mentioned earlier the NJ did, so maybe Loree latched onto some U.S. orders for NYC and picked it up for a bulk price. I remember Tom Carter, when he was President of the KCS, telling me that he was happy to have bought some very good 127 DY relayer rail that came from the Cleveland Union Terminal, around 1978. CUT never saw any heavy wheel loads, so the rail was almost as good as new.