In a letter to her brother Huma referred to Castle as either Clinton or the White House. I've seen other references to both…
That's the whole point… Q has always said future to prove past, this is past proves future… odd.
Where was the photo taken?
Elkhart uses very similar letter number design and gold front lettering look at the pic for R2
http://www.indianafiretrucks.com/pages/elkhart/elkhart_2-4.html