Where is the vacuum tube of Chang 'an Yidong engine?

Where is the vacuum tube of Chang 'an Yidong engine? It's on the intake pipe. There is a white iron pipe on it (the cars I have repaired are basically white). Then there is a tube under the fuse box. The engine intake manifold is connected to the iron pipe (under the car belly). A pipe and an iron pipe are lined up, which is the engine brake vacuum tube. And then connected to the brake master cylinder through a hose.