Bachmann's 42' 3-Dome Tank Car is present at the start of the HO-scale rolling stock offerings in 1970. The 42' Single Dome Tank Car's history is less well documented. For catalog appearances one will not find this car among freight cars until the early 1990s with a trio of roadnames: Philips 66, Shell, and Cyanamid. Examples examined pre-date this early '90s group. Shown above you'll see a Penn Salt example in late '70s packaging and it carries a '70s stock number. The open top packaged Shell model is an early '80s offering. Niether got cataloged.