Don't know if I need to clear something up here.
Marler Haley was/is a display system, and not the name of the posters. The posters started being call so, purely as that's where they were used, on that display system, which held 4 dc's and 2 Quads, one of which was the General release Quad.
Those DC's, Matt were mostly used on Buses, as were most DC's.
As for the two Quads joining together, there was more than likely a 4 sht released with the same design, but the Quads were also used separately.. as they are basically a 4 sht cut in half.