Atlas 50006301 N Master 20,700 Gallon Tank Car, GATX #99564Atlas 50006301 N Master 20,700 Gallon Tank Car, GATX #99564 Atlas Item #: 50006301 The 20,700 gallon tank car was introduced in the mid Sixties by General American Transportation Corporation, more commonly known simply as GATX. The design is a general purpose, non insulated, non pressure tank car. The Atlas model recreates two major saddle variations (Type 10 and Type 20) and two top platform variations (one and two piece). The more common products