Replacing Stuf Unit Frame's role icons

[Heybarbaruiva]

As the title says, I'd like to change the role textures (DPS, Healer and Tank) Stuf Unit Frames uses on it's raid frames to custom ones I've been working on. I didn't find any .tga or .blp files inside Stuf's folders so I have no idea how to change it. Any of the more lua-knowledgeable people out there care to help me out?

Tyvm!