Hi targetharvard,
The OG2017 is two 'iterations' away from the OG2013 (the OG2013 and OG2015 are the SAME book). The OG2016 replaced about 25% of the content from the OG2015; the OG2017 replaced about 130 questions from the OG2017. This is meant to say that a significant amount of content between the OG2013 and OG2017 is different. Unfortunately, I don't believe anyone did a 'breakdown' of the differences between those two books (we did a breakdown of the OG2016 vs. OG2015 and a separate breakdown of the OG2017 vs. the OG2016, but I don't think that you want to work through 2 separate documents (by cross-linking the data) to find the "new" questions in the OG2017. All things being equal, if you've worked through the OG2013 already, then you could likely 'eyeball' the OG2017 and find all of the 'new' questions.
GMAT assassins aren't born, they're made,
Rich