Say Why Blower Manifold??

I apologize if this is not posted in the correct area. I am still researching parts from my FIL and can not find much on this. From some reading, some say it is rare however I don't know. I would like to know what it is worth, I am going to Spring Carlisle. Please this is not a for sale thread if you have any specific questions please send me a PM.

Thanks for the help.