One of the reasons we get a stream of unusual freighters into Paine Field is the delivery of sections of fuselage for the production lines.  This can include front fuselage sections, center wing boxes and empennage elements.  One afternoon an Antonov showed up to deliver some of these parts.  While getting the plane arriving was why I was there, it was interesting to see these chunks of future planes (I believe these were for the 767/KC-46 line) being offloaded and driven off to be used.