Texture files are specific to the model. So you could not take textures from one aircraft and stick them in another.
Inside the textures folder you will find textures for a specific model. For example TDS Boeing 737-800. Even then you need to get the correct base model as engines, winglets, etc, will vary.
There is a good KC135 here https://simviation.com/1/search?submit= ... &x=11&y=12
It contains a paintkit but only flat BMP files. I only paint textures when there is a layered .PSD format paintkit.
However if you can provide an image of what you want I will take a look.