The specs indicate that the crankset on this bike is the S1000 crankset. However the arm is stamped with X56LAAA 1 on the back side at the top and it also has a 175 on the backside along the bottom edge...which I assume is the 175mm length.
Does the first two digits mean it's an X5 crank arm? It looks similar to an X5....the screen printing is different than mine. The s1000 listing from trek is what is confusing me.