Go to the link above and use the radio buttons to find out the appropriate engine.
The calculator indicates both the location of the engine, and its number in packed bag form, so if you or someone has already packed a bag incorrectly or accidentally.
For direct link sharing:
Worst Case Scenario: The 50/50 Distributions
The following distributions create a rare 50/50 chance where two tanks match the information. Based on user observations, the following appear to both meet the requirements. There is a 50/50 chance that you will get it correct due to both of the tanks being equal. Take both, and hope your first one is right.
2 Tubes, Helium, Greater Than or Equal (#3 or #6)
3 Tubes, Helium, Less Than or Equal (#7 or #10)
Kudos for the info provided by Insert_Sex_Here @ Reddit and the original images on Imgur[imgur.com] by REACHGROUND.