I want to say the OEM filter was located at the input to the carburetor. It was a metal (brass?) fitting with a screen-type filter element inside. Maybe an inch or two long that threaded between the hard fuel line and the carb body - badically part of the carb like Redstang said (welcome to the site!).
But it's been years since I looked my original 2100 and my memory is getting old. I inserted an aftermarket filter between the pump and my Holley carb years ago.