All right brain-trust / fuel tank question

This is tough
I bought a tank off of ebay. I checked to make sure it was for a 2000 Nomad and it was. I painted this thing (see other thread) and now have found that it is in fact for a 2000 California (or as I call it communist) model.

Question is... I only have a vent tube. Which line of the tank do I hook it to. The one marked with blue or the one marked with red? I am going to cap off the other one.

Whatcha got BD ?