ok, so I actually don't know what I'm doing (still learning how to do mods), and I hope you don't mind me trying to help, but I was able to get the mod, opened it up and been testing with a separate "test" copy. So far this is what I've got...

I can now delete the mod and log into profile (b4 I couldn't, it would still crash). The game defaulted the truck to a Scania R 2012 (the games' "fallback" function), and I sold it.

Then saved the game so I have a clean spot to go back to if something fails.

Reinstalled the "test version" with a few tweaks (some file renaming to make more normal to the rest of the mod, and edited the .sii files to work with the new file names). Now I can view the truck in Truck Viewer, I can see the truck in the Dealer, and I can even modify with any accessory available with no errors and purchase the truck, and even drive it around (still with no errors). I can visit the Garage for repairs and maintenance, and I can go into the Garage/Truck Manager. Everything seems like it's working fine until I go to the main/escape/exit screen (desktop screen). And then that's where it crashes. Only there now.

That's a lot more than I could do b4. So, now I'm wondering if there is something wrong internally with one of the files that has to do with displaying the truck on the Desktop Screen. I did notice some differences between this and other working mods, the way the .sii files were structured or written in the def/vehicle/truck_dealer/scania & def/vehicle/truck_desktop folders. Being the problem is now only on the "desktop" and I didn't touch those folder/files yet... maybe there, idk. But everything else I can get working now.

But I'm a little tired now so I thought to give you an update of what I've done. If you want specifics pm me and I'll send you the "test" version I've been working with. I hope this is some help to you.