Lionel 6-83107 - Daylight 21" Passenger Car "Southern Pacific"
21" each. Min o-54
The mth set I got on ebay, 20-6623 are 18" each o42
Mth 2017 catalog, they are 19" each. Min o-42
Just going by what I saw at the store.. if Lionel makes a shorter 18" version.. I'm not aware.. I haven't really been all over their site. Info above from Mr. Muffins trains, place where I saw them at.