I don't think it's a 1N, this one has a 20'' kick and a mounted cymbal arm holder on the kick.I'm also wondering if maybe originally it had a 12 x 8 tom.If the original owner had added a 13 x 9 , maybe that's when he had the Ludwig double tom mount post installed to have both toms playable.Then fast forward to 2015 and the 12 x 8 is gone which leaves the 13 x 9 with it's diamond plate facing the audience...