Peter, before you start collecting those numerous add-on cars that Craig mentioned, procede cautiously. Unlike later and recent PE berks, those first run ones were manufactured with small series 1 motors, meant for and sufficient in their time for powering the basic number of cars original to those sets and not many more since back when those first sets were manufactured Lionel likely never envisioned the PE becoming the force it is today with the plethora of add-on cars since produced for it.
While it may run fine now, once additional cars are added to its consist, your PE berk will begin running progressively slower and the stress to its smaller motor of pulling those add-on cars will eventually cause overheating followed by failure. I speak from experience as that's what happened to my seies 1PE set's berk. (Fortunately Lionel ultimately replaced it with a conventional berk that had a series two motor.)
Btw, due to the design of series 1 motor frames, series 2 motors cannot be substituted into a series 1 PE berk frame.
So, Peter, enjoy your new set. It's found a great new home but procede judiciously in accumulating additional cars to run with it.