I would suggest unbolting that hanger rod and then take the one bolt out that is located in between the two boxes about halfway up the boxes. It is I believe a 3/8 not which threads on to a stud which is attached to the a/c box. Just remove that nut and the hanger. Take your two heater hoses off on the firewall. You may have to disconnect a couple of the vacuum pod linkages which are just clips. Make sure you mark them where they go. You should then be able to just pull the housing completely off and then you can remove those really tough clips that hold the two halves together. Best done on the bench. I would also get a new foam gasket set from maybe Detroit muscle. I was trying to load a picture of mine on the bench but the file size is toooo big. I will try and resize it. Here we go. You can see the small bracket that is inside the fresh air chamber. This is the bracket that holds the hanging rod. You can also see two of the clips that hold the two halves together. I had my entire unit on the bench for a rebuild. I hope this picture gives you a sense of what things are and where they are.