That's the preheat(er) or stovepipe tube on the left heater box/heat exchanger. Beetle, bus, split or earlybay doesn't matter as they all work the same with the correct parts for your bus. Here are some links to more info ...
https://www.thesamba.com/vw/forum/viewtopic.php?t=389108
https://www.thesamba.com/vw/forum/viewtopic.php?t=394957