heater box install?

[SS Shaun]

so as i was getting all the stuff together for the Christmas Decor i was in my attic and i found my heater! i didnt know i even had this...lol So no my question to you guys is is it easy to install? where does it go on the car? I know it bolts on somewhere by the firewall but i am not sure where exactly. I am asking because my firewall has a bunch of sheet metal riveted in and i dont want to remove something if i cant fill it in. some advice and pictures would be great