Body paint color, all the plugs and wires free of paint because they were installed after the car was painted. The insides of the quarter panels should be undercoated, too, then painted. Helped with both sound deadening and things sliding around the trunk from denting the panels from the inside out.
There should be some undercoat overspray along the fenderwell extensions, too. I remember digging the stuff off mine when I painted it, so I imagine they had their undercoat gun in hand, reached in, sprayed the corner and over the wheel well, but did not get any on the gas filler tube, cross members, wires, etc..