now that you mention it that does make sense the one I've currently got my 5.3 in is a 67 and has these vents. However I have pulled tanks out of 69's and 72's that didnt have them... is the main reason you recomend welding a bung at the bottom of the tank due to making the pump work to hard to pull fuel? Is there a reason classic trucks didnt do so ( on this build
http://www.classictrucks.com/tech/09...l/viewall.html) , and many people havent done so on their builds with stock tanks? has anybody runing this set up on here experienced any issues with their pumps?