I see two if them at the bottom, but it sure feels like there's more holding it in there than those two screws. I see one that almost looks like it comes in from the firewall.

I'm trying to change my heater box because the lever that controls the door is broke off. I already have the dash pulled about halfway back.

 

I can tell you that one is a PITA to get to. I believe there is four total, but the one at the top of the case behind the dash is a real pain. The previous owner just broke the thing off on mine.... Try not to do that on yours, as heat flow to the dash vents will suck. Get a small flashlight and see if you can find the other(s).

 

I'll have to look closer the next day I get a chance to mess with it. Even with the dash pulled back it's still hard to get to, sure is a lot of trouble just for a broken lever.

 

there is 4 under the hood, four inside the car. All 10mm bolts. be sure to remove the drier (silver cylinder in front of box) before pulling the assembly out.