I kept browsing and ended up finding something, cited from book (no idea of its title or author)
white page, large title "ARMAMENT" subdivided into 3 categories + 3 images of the sky van displaying armament (much like the drawings we shared here), 1st drawing with Gun-pod (side view), seconds with rocket pod (frontal view), 3rd with Hellcat missile (sideview).
LIGHT MACHINE GUNS
Both external and internal gun installations are possible with the COIN Skyvan. The standards wing pylon accepts the Universal Twin 7.62mm Machine Gun Pod.
This self contained weapon which is defined to provide heavy suppressive fire for ground attack or counter insurgency roles offer a rate of fire of 850/950 rounds per minute.
The exceptionally strong floor of the fuselage is ideal for installing conventional light machine-guns (7.62mm) or 20mm automatic cannons firing through the side and read fuselage doors for strike missions against ground forces.
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AIR TO GROUND ROCKETS
Modern attack philosophy favours the large stroke are without loss of density which ensures a greater "Kill" probability. The 2-inch Rocket system is designed to this end because low front large of the rocket permits high density loading. The high "Kill" potential, coupled with with the low cost of the rockets, gives an excellent cost/effectiveness ratio. The Skyvan installation, similar to that on such present day ground attack aircraft as the Harrier, Panthom, Etc, retains the capability of pairs or ripple firing. Alternatively the 68mm rocket can be installed.
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GUIDED MISSILES
Four Short "HELLCAT" air-to-ground guided missiles mounted on underwing pylons provide the COIN Skyvan with the most sophisticated armament offered on any fixed wing light aircraft.
HELLCAT, which is developed form the well proven SeaCat missile and adapted for aerial launching packs the punch of a 6 inch shell. It can be fired from at a considerable range at difficult targets, such as light ships or armored ground vehicles, with pinpoint accuracy thus giving the SKYVAN an exceptional "Stand-off" attack capability.
Something i wanted to add, the missiles are on the horizontal position, much like CJGibson's illustrations and as soon as i can find the book ill try to share about it.