As you probably guessed, I am a complete novice to modding and the like. I have been trying to create custom lettering for the Grand Marshal, but have had little success. I'd just like to know *everything* wrong with my file, so I can have a better idea of what needs to be fixed. (The file also includes a 'detective' skin for the Grand Marshal, which works fine - don't mess with that)
First major problem, you have nothing on your diffusemap for the detective, the detective is blank. Secondly, the mesh referenced fullsize_lettering_police doesn't exist stock, nor is it included in your files so there is nothing for beam to load in.
I've done some work, but I've run into another problem: The area circled in red should have the 'police interceptor' badge. Please check my edited file:
By changing the layer of the diffusemap from 0 to 1 I can get the badge to appear, however there are unexplained objects around in the surrounding space, hopefully I can track those down for you.
This should work, I honestly have very little idea of what I did to fix it as I had to reset the layer back to 0. My best guess is that I made the dynamic cubemap false. It may be easier for you to check by comparing the old and new files.