you can just create image points on the truck spawner then Set Position of truck to Object (image point 2 or whatever).
In my game I have a space ship, when I edit that sprite I made numerous image points. 1 for where the laser will start (just in front of the ship), 2 where the engine exhaust goes (behind the ship), 3 where damage text appears to show how much damage the ship has taken. This last image point it way outside the sprite box, it's a good 100 px away.. but its a good way to get a relative position.
If I am creating an object that is somehow related to another object. Then I always have the related object "Spawn" the new object.