Honestly, just take a guess and go with it. It's important for us to assemble things correctly, and when doing that mini for the 2009 diorama, I sat there with multiple TROs open and still couldn't be sure which barrels were right. This is an example of more pieces/more options being bad: it adds frustration for no real gain. Chances are no one will ever challenge your choice of barrels regardless of what variant you claim. Pick what you like the look of.