Pierburg 1b3 carb rear vacuum ports x2

Hi, does anyone know what the x2 ports on the rear bulkhead side of the carb are meant to connect to? Mine are currently not connected to anything

The port in the foreground in your photo connects to the pull-down unit and the one further away connects to the air filter. The ports highlighted in yellow on your diagram are fuel lines on the opposite side of the carb

There's actually 3 ports, the furthest one is connected to the airbox, the middle one is now connected to the pull down unit but the closest one I have no idea? Any ideas there this one goes?

I'm struggling to find more than 2 vacuum ports on the bulkhead side of the carb. Any chance of a picture showing all 3, and so we can see which 2 you have connected?