Lionel has had these nice true O DD cars for many years, not sure why they would change to P.R.
Pecos cars can be identified by their oversized grab irons. They also have more of an overhang on o36 curves than any other 50' car made. They are slightly wider due to the door guide compared to the other MFG's. I had to shave a tunnel wall curve and platform edge as they would rub against them when passing. Stamp markings on the trucks are the best but now I noticed added markings to the new Lionel truck design, gen 3.