How to remove Heater/AC diverter Box

Hi,
On my 84, I need to remove the heater diverter box (the part behind the dash)

I'm trying to figure out how this comes off? Does the heater box (the part under the hood) need to come off, to gain access to the screws?

I'm looking at it from inside the car, and I can't find anymore screws holding this on, but it won't come off.

If I remember correctly some of the screws on the box under the hood hold it on the insde as well.

I finally got it out yesterday, and yes. There is 1bolt that goes from the outside.
Luckily, I was able to move the little flap door and reach my hand inside and able to find it and get it off. Took forever , but glad I didn't have to take that heater box thing off.

What a stupid design. Why have 1 bolt be different from all the others.