Stanley #140 Rabbet and block plane, 7″L, 1 3/4″W (1 5/8″, 1936 on), 1 1/8lbs, 1896-1944.
Quote from Supertool.com
“This is a very useful plane, and is one of Stanley’s better products (it would have been even better if they didn’t supply it with the cheesy lever cap wheel like that found on the #110, et al, and if it had an adjustable mouth). The plane can be used to trim crossgrain rabbets, the cheeks of tenons, for cutting rabbets, general block plane work, etc. The plane’s number is embossed on its heel.”
The flat lever adjustment mechanism is found on the earlier model.