I had to have the hoppers remade out of sheet metal, the old ones were to far gone to get any numbers off of. 

If I am not mistaken the plates have a 6 digit number cast on the back side of them, but am not sure. I can try to get a picture of them, and I will also write the numbers down.

Also, there is not serial number plate/tag anywere on the planter that I can find, were would it be located???