Swapping AC into my 70 K5 from a 72 donor K5 when I found out that a little flipper door is missing. The part I need is on the interior side of the firewall and is the first piece that bolts up to the biggest piece that has the heater core in it. It is the box that diverts the air to the defroster ducts. I've seen them new for abut 90 something dollars. Anyone have one that they don't need for less?