You can't use the truck gearbox. Because 600xp220 is a heavy-duty industrial gear oil, it is never recommended to be used in shifting gearboxes. According to relevant information, 600xp220 lubricating oil is suitable for various industrial applications and ships, especially spur gears, helical gears, bevel gears and turbine drives. Containing a large amount of sulfur and phosphorus extreme pressure antiwear agents, it will corrode gear oil with medium load and oil seal of gearbox with medium load, so it is not recommended to use it in gear shifting gearbox.