At least shimano stamps a part number on most of its parts. I mostly repair 70s-80s bikes and often encounter an “I’ve never seen this before”, or a situation w

At least shimano stamps a part number on most of its parts. I mostly repair 70s-80s bikes and often encounter an “I’ve never seen this before”, or a situation where parts have the same branding on them, but clearly went through multiple (undocumented) iterations. There ends up being a lot of “close enough” substitutions. E.g. cones on axles.