Hi there
Recently I have been trying to use a hi res cockpit for AH 64D from Cockpits.nl however the DDS's were flipped (and my knowledge in that field is pretty much non existent) so instead of trying to figure things out I have just converted pretty much everything to hi res BMPs (+4 TGA's) and it works.
If you want to go this route, just go to "...\cohokum\graphics\textures\cockpit\ah-64d-cockpit", remove everything from that folder, download the below RAR file:
https://drive.google.com/open?id=1wmsJxLyrLaGEYXrdtWUn-peLg8UMTK7x and extract all files into the ah-64d-cockpit folder. Simple as that and it works. I have spent some time yesterday testing it and came across some weird issues so please remove all files from the ah-64d-cockpit folder first!! Otherwise your PC will blow up and our precious planet will teleport to a different dimension causing pain, chaos and death...ok maybe not
I have attached some screenshots below to prove it works.
Enjoy