Mike D, yes Lionel MPC did have a very rudimentary sound system they utilized all the way up to at least 1987. It consisted of a round container fitted underneath the tender body which would come into contact with the middle rail. It was covered with a rubber like substance which would aid it in turning as the train ran across the middle rail. The round container was filled with BB like metal balls which was supposed to simulate a Choo Choo sound as it turned while the train was running. It was strictly a mechanical device and not electrical. My daughter-in-law's mother gifted me her late husband's train which has this device. It is listed as the MOPAR Express and has a 4-4-2 Atlantic type die cast engine for its motive power and three or four freight cars. The outfit was manufactured in 1987. I only ran it once and then packed it away. Believe me when I say the "sound system", if you want to call it that , was quite rudimentary. Curiously, there was not one word to be found in the operating instruction pamphlet about this sound system.
Also, the set came with an oval of 027 track and a red 25 watt transformer.
