Agricultural wagons with animals in place of an engine didn't have a real plate, but just little tags to show that taxes had been paid. They had three tags: the first one (first picture on the first line) was just a print "CARRO AGRICOLO" (agricultural wagon) and was not always present. The second showed that actually the tax had been paid and was not different from those for cars seen above (second, third and forth pictures on the first line). Last there was the real plate of the wagon and it lasted two years (all other pictures). As you can see in the pictures these were hand made, writing the name of the owner on the tag and were different in each town: I included many examples to show that actually there was not a precise rule about them.
You can enlarge each picture just clicking on it.
I want to thank Louis Fierens, Giancarlo Raposo and Alessandro Libanore for all these pictures!