On page 10 of v2.2, the example item is listed as "2D4 (2 Load x Grade 6 = Value 12)." I believe it should read "2D6" instead.
That is actually correct. It’s the fiddliest bit of the game. Grade both has a value and a die associated with it. There is a table on page page 25, in the item section, that breaks down how Grades and their associated dice interact. I’ll add a bit more of an explanation earlier too, since it is the most confusing aspect of the game.