I recently obtained an original copy of a 1923 Stanley promotional pamphlet which illustrates and describes the Bed Rock Planes in production at that time.
When he saw the plane said: "you are lucky, Giuliano, this is a type 13 SW Stanley Bailey.
If not, your plane is a Type 11 and dates between 19.
NOTE: This type discussion, along with the foregoing material, is based on personal examination of numerous Bed Rock specimens since 1973. Frog & bed machined & mated 100%; inclined frog seat. Keen Kutter Bed Rocks had plain lever caps and Winchester Bed Rocks had Winchester marked lever caps.
Unfortunately, many plane types share the same bed markings, so other features are also used in dating.
Determine if the plane has a raised, broad, and flat rib casting at the toe and heel.
Determine if your plane has any "wartime features" such as a handle or knob with red or black paint or stain or a steel or hard rubber depth-adjustment nut.
If so, you have a Type 17 plane that dates between 19.
Each type has subtle differences that distinguish it from the other types, such as variations in parts and different marks cast into the metal like the plane size number or patent numbers or dates.
Familiarize yourself with the names of the various parts of the tool using a Stanley diagram (see Reference 3). Note whether you see any patent dates cast into the bed and if so, how many.