Sitting in the hot sun on a hot humid day using the Dremel outfitted with a sanding drum grinding away fiberglass to get close to the scribe lines in the area where the oil cooler will mount.
Once the Dremel work was completed, the cooling duct was hand sanded using a sanding block and tweaked in a couple of places with a file.
Hand sanding the edge of the fiberglass duct to the scribe lines.
After the sanding was completed, the opening in the duct was placed over the oil cooler and the overall fit was checked.
Overall fit is looking good at this point, just needs a couple of tweaks.
A couple of spots were tweaked a little and then the frame of the cooler box was clamped to the duct so the two nutplate holes on the top flange of the oil cooler box can be match drilled into the fiberglass duct.
The oil cooler assembly clamped to the duct after being centered in the opening and ready to be flipped over for drilling.With the oil cooler assembly now clamped onto the fiberglass duct, it's in position to match drill the fiberglass duct using the two nutplate holes that can be seen on the top flange of the oil cooler box.
By this time it was getting late, so stopped short of drilling the holes so that will be the next task during the next work session.