This part seem to be left out in the paintkit when it comes to dirt. There is literally none on it. The fuselage part just under it got a bit more grease than the rest of the fuselage, so the difference is notable. Don't really know how to adjust that properly. I don't want to get rid of the weathering on the fuselage completely, the liveries already look rather clean.

Check the description above. You need to install the box_commons.zip as well to get it loaded fully.

Let's say you install the all regular Aerologic livery first according to the instruction and want to install the op DHL next you don't need to select the 'pmdg_777f_box_commons' again for installation, works the same vice versa. The Aerologic Commons are literally the same for both op DHL and regular Aerologic liveries. The OC is complaining there as you can't obviously install the same livery twice. I needed to include the Aerologic Commons in both uploads so they work independently.
As for the weather, I am aware some of you want a bit more dirt. I have done a quite dirty Fedex livery and while doing it I found the PMDG dirt layers rather suboptimal. The front and the rear parts are quite good. But the middle part starting somewhere behind the front door and ending before the main cargo door it looks like someone at the PMDG art department created a dirt layer for a small fuselage parts there and copy pasted it like 8 or 9 times to fill the rest. If I make the weather effect a bit stronger, I can't unsee it anymore. It just doesn't look realistic at all, as weather/dirt don't follow symmetry. E.g. there is a larger part of dirt coming from the roof which is multiplied several time with the same spacing and same direction.
It looks like someone plastered a wall with the same pattern. That's not how weather/dirt works. I hope you can understand my explanation and lead you to a 5-star rating.