[HELP] Vehicle Modification in Blender

Hi, I’m having trouble modifying vehicles in Blender. I’m trying to download 3D models to apply to my vehicle. Once they’re applied and merged into the hierarchy along with the chassis, I export the vehicle, upload it to my localhost, and it loses its wheels, and the modification doesn’t apply.

The other day I had the theory that it was because it wasn’t a 3D model properly compatible with GTA. So I grabbed a sword and yes, the model was saved, even though the vehicle crashed, then I removed the swords and added some wings, it worked more or less, the texture was bugged in-game, but the vehicle didn’t have wheels. So if someone can tell me why my exports have bugged textures (they look semi-transparent or torn), and then the vehicle spawns without wheels and even though I attach them to the chassis, they don’t turn, but remain static…