@Ted S posted:Andre, the LC+ Mikado you posted is definitely "traditional" size. It's smaller than a 736 Berkshire, maybe even close to 3/16" scale with O-gauge wheel spacing. That being said, I think it's a good looking and well-built loco that should run great on sharp toy-train curves. The LionChief Hudsons, Pacifics, and Berkshires are traditionally sized, i.e., smaller than 1/4" scale. The steam switchers, Camelback, and most of the diesels are scale or near-scale sized.
Yes, all the steam engines (except the A-5 and Camelback , which are scale, as John said) are traditional size. As far as the diesels, as others have said, the RS-3s are scale. Also scale sized are the Geeps (GP9, for example), and also the FT diesels. The others are smaller than scale, such as the U-36B and the ET44ac, and the LionChief electrics are also traditional sized locos, which include the Rectifiers and GG1s.