[cruzn72]

I think the heater box Cobalt is talking about is the big ugly box in the engine compartment.

The one thing he did not mention is the nuts on the bottom of the box. There are studs coming out of the cab that hold the box on. I do not know if there is a secret way to get to the one nearest the fender, it is a pain. I guess you have to take off the front sheet metal, yeah right. We finally drilled a hole in the inner fender and put a socket with extension through to get to the nut.

The first time I under took this journey, I took the hood off. What a mistake that was. I had to replace another core last winter and left the hood on. I can't remember how I got the box off but it came off and went back on.

Hope this also helps.