The tube from the plenum (still available) is open, but includes a foam screen in the end. The hose from the bottom of the Air cleaner housing is essentially the same tube, but originally was plugged with a slotted cap. Naturally, this is no longer available
I just bought two of the tubes, then cut the one for the cleaner housing to length and plugged it up with a small plastic plug. It's a drain for the cleaner box that needs to be cleared occasionally, so the plug must be removable.
Hope this is what you're looking for.