#2 & #3 will both work, the #6 works with all the 3 liter, 4 liter jugs and 1/2 gallon jugs.
Some of the 'gallon' jugs that we get in Canada take a #7.5 or 8 bung.
Steve
Here is a bung sizing chart for you that will get you much better to the size needed.
http://www.finevinewines.com/Bung_Sizing_Chart.htm
Yah when I had the store I had a similar chart that I would hand out. Lots of people don't seem to be able to measure, cause people still got the wrong one, and usually by 2 or 3 numbers not just the next size.Here is a bung sizing chart for you that will get you much better to the size needed.
http://www.finevinewines.com/Bung_Sizing_Chart.htm
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