@Stampywhen any modular car type vehicle spawns, it will spawn with a randomized code. I will add a config option for it to have the player add a code on first spawn and then attempt to replicate that code on every respawn with the next update.
As for the no permission, you are using a shop / reseller item to spawn the vehicle which gave you the permission for the actual vehicle yet you havent given yourself the permission to spawn any vehicle with the /gunship or /gs command. This is not done automatically and you need to assign you / anyone else trying to spawn any vehicle the gunship.spawn permission