I re-undercoated the cannons with Vallejo Model Air Bright Brass then a wash of Agrax Earthshade. The flesh was Bugman's Glow washed with the old Ogryn Flesh and then darkened with Druchii Violet. The red was Mephiston Red with Earthshade in the recesses and highlighted with Fire Dragon Bright.
I applied some Nihilakh Oxide in sections to the brass as a bright contrast along with the highlighted bone.
I still have to add the crew. It will be a Bloodletter and cultist conversion on each rig. The cultists to fit in with ones I have in my Plaguebearer and Pink Horror units.