The outer box has a known location outside, in relation to the fan blower. The hole by the blower at the 2:00 and the 7:00 position fit both the non-ac and ac heater box.
You can see that there is really not a lot to close up with a non-ac box vs an ac box.
Here is the only gap, which is at the bottom of the box and pretty much out of sight.
Here is a pic of the inner box mounted on the inside and the firewall prior to being cut.
Here Ive traced where I am going to cut:
Here is the hole cut, no inner box installed. Ive cleaned up the edges with a file but will probably still do some fine trimming before I seal everything up.
Inner box back in:
Box before paint, blasting
Box after blasting
I did not show the pics but I put a shim to cover the gap at the bottom of the box then filled it in and painted that area. Box installed, tidied up, be hard pressed to tell this was an AC car at one time!
Small spot under the box but youll never be able to tell once engine and everything in the car.
Total cost of box overhaul: $40, including paint.
Add in the heater core: $75 total.
