A PM I received from another forum member alerted me to a mistake in my listing. I had the headers listed as having 1-3/4" primaries. However, Dynatech does not make these headers with 1-3/4" primaries. They are only available with 1-7/8" primaries. That information can be found here, by selecting either the 2.5" or 3" system on the left-hand side of the webpage:
My original post has been updated accordingly.