360 la weighted flex plate do I need to rebalance?

Yes my engine is still EXTERNALLY balanced. And I will be using a 46rh transmission behind the engine, and when I called PATC after the guy said I wouldn't miss something like that I then asked what could you guys do send me a shipping label and send it back to put the weight on or whatever. I also asked if maybe he put the weight elsewhere on the converter and he simply said nope if it's not on the front then there are no weights on it at all. He told me I could also ship it back but I would have to pay return shipping I live in MI and patc is in Louisiana, can't imagine the shipping on that. Or he said I could buy a b&m flex plate, really not much of any help IMHO.
This is their screwup and not yours. If they won't pick up the tab for their mistake, I'd dispute the charge with your credit card company- you did not receive what you ordered.