Vehicles.meta you have not provided that file, there is only the text file?

@Carlos_Moory Yes, copies the contents and substitutes yours.

This is very nizeee!

@ReNNie Thanks

@carloxfranco another nice trailer mod! Thanks for sharing :) Can I change the extras when I have spawned the trailer with a trainer or do they spawn with random extras?

@kingle92 Thank you,

I think that because of the trainer you can not change extra in trailers, it always appears randomly.

@carloxfranco yeah, you can't "enter" the trailer like a car so the trainer don't work. I have some car trailers installed where you could enter the trailer like a car (invisible seat) to open or close the door (ramp).
https://www.gta5-mods.com/vehicles/fulvia-hf-transport-mod-add-on-replace
Don't know whether this can also be done with truck trailers. But that could be a way to choose liveries or extras even for trailers!

@kingle92 Okay, I'm realizing the idea I'm going to take a look and even digress this suggestion, which seems a great idea.