Evans built these cars about 1967 IIRC. 50 cars for the Pittsburg and Lake Erie, 10 cars for the Bessemer and Lake Erie. S scale drawings were published in the August 1968 Model Railroader with a minimal background information. The cars were a great idea of protecting steel coil loads on paper but proved to be less than spectacular in reality. The clamshell doors were easily damaged in the steel mill environment and the doors were also known to unexpectedly drop when being opened endangering the workers. Many of the cars were converted to use more conventional lift off covers of steel or fiberglass rather early in their lives. Others were converted to open gondolas even being used to haul steel scrap loads. Bessemer cars lasted at least into the late 90s if not beyond. P&LE cars were disposed of after they went out of business, perhaps resold but may have been scrapped too.
Some pictures of the variations of the B&LE cars have been discussed recently on the Bessemer Message Board. There are a few pages of information on the P&LE cars in a paperback book published about P&LE Gondolas some years ago. HO plastic model is only one I know of, nothing else in brass or in other scales that I know about. Reasonable scratch build in other scales as the cars were welded construction.
There's a book titled, "P&LE's Gondola Cars" by Gorzoch, Polaritz, and Sparico c. 2003. (Kahndog Publications) It contains a lot of info about these cars, and is a handy reference for modelling the P&LE.