How much is the Louisiana tax credit for 2006 for a Prius?

I've been passed from one state Department of Revenue employee to another trying to find out how much is the Louisiana income tax credit in 2006 for a Prius? None of them have even heard of it. I know I read somewhere that Louisiana does in fact give a credit, somewhere around $400 or $450, but I can't recall where I read it.

Does anyone know of a state-by-state list of the amount of the tax credit for a 2006 Prius?

Thanks.