Chassis Codes?

I'm currently driving a 2016 Prius 3 Touring and was wondering if anyone knows about chassis codes. I'm trying to purchase a part and the supplier is asking for chassis codes to confirm fitment. Supposedly XW50 cars are subdivided into either ZVW50 or ZVW51. Toyota North America doesn't seem to know and referred me to my local dealer service department. They're looking into it, but don't have a clear answer yet. Said it might be stamped somewhere inside engine compartment. Thing is, I'd have to pay the return freight if I order the wrong part, and they're quite heavy so shipping back won't be cheap. Thanks in advance.