What is this notched or angled 1x2? It looks old. the only markings on it is LEGOS stamped on the top of the stud holes, and a number 2 stamped on the bottom. It looks like a normal 1x2 with a slight triangle taken out of each side. 

I couldn't come up with the right words to describe this piece to determine on my own what it's called or what set it might have been from. But maybe someone else has seen this before?
Old style minifig legs (70s). Sets that have it