How to replac vacuum line part number 24506734 on 1998 Chevy Venture

SOURCE: where does the vacuum line on air intake duct

Are you referring to the plastic line that comes out of the top of the duct, turns and disappears toward the back of the engine? That line goes to the top of the rear valve cover. Use a flashlight and look for the hole on the top of the back valve cover. Look to the right and below the coils. It's tough to see but you can see it. Be careful, sometimes the plastic line can be brittle and break.