We're sure most of you gearheads can probably give a lecture on the mechanics of a differential gear. Even so, this awesome tutorial from the 1930s is still fun to watch. Everything makes complete sense without a lick of CGI or 3D animation, but the YouTube channel tacked on a quick cartoon in case the classic video wasn't clear enough. Take a look inside your great-grandfather's ride and see how little some things have changed. This is so cool!