I always get asked about knuckle block planes. Stanley, Sargent, Union, and many others made a knuckle block and they made them for many other brands. Some never have a name stamped other than the cutter. These often got changed or lost.
So who made that block plane (other block plane post)
Here are some clues
Sargent Knuckle Blocks
Union Block Planes
Stanley Block Planes
Siegley (Stanley made)
Ohio Tools (along with some Keen Kutters made by Ohio Tools)
An Ohio Made Keen Kutter Block Plane