Thank you Tyrion,
Sorry for posting in the wrong section.
I think I found the answer in:
CAPTAIN SIM COMMUNITY FORUM › Legendary C-130 (FS9) › C-130 - General Discussion › Legendary C-130 Extra Pack Support,
if I look at reply 8:
It appears to be the wrong texture format. I will try it at a later stage.
I will convert all the textures of one model to older FS2004 format and see what it does, after I have made a backup of course. To just copy the files over as this guy suggested in reply 8 did not work. But I think I will succeed at a later stage. I will eliminate one thing at a time and later everything except 1 until I find the answer.
Regards
Johan