A fuel cell stack includes an endplate assembly having a structural endplate. An insulator plate has a second exterior surface contacting a first interior surface of the structural endplate and a second interior surface on an opposite side of the insulator plate. A third plate has a third exterior surface contacting the second interior surface and a third interior surface on an opposite side of the third plate relative to the insulator plate. The third interior surface and third exterior surface are substantially flat. The second interior surface and the third exterior surface contact each other substantially continuously in a longitudinal direction and a lateral direction, and are flat and substantially parallel to each other. The second exterior surface is contoured such that the second exterior surface is not flat and is substantially non-parallel relative to the third interior surface.