Probably the weight?
I ship stuff by container all the time...we have to mark each item as to its weight. If that thing is a silo thingy, 5000 lbs seems to be about right.
If the weight is in pounds, it would greatly reduce the possibilities for location of origin.
It would more than likely have been posted “Tare: 5580” if that was the posted weight of this thing. As well it would have other such markings for Net capacity and gross weight I should think. I think the 5580 is an I.D. number.