In 1974, Marx introduced a steam freight train set, catalog number 2905, it called The Reliable that ran on a 6 volt lantern battery and sold through discount stores. If you have one today, it’s worth more than its original retail price, even adjusted for inflation.
The Marx Reliable was part of the Great American Railroads series. It had catalog number 2905 and was sold only in 1974 and 1975.