[kaz442]

No need to take off the fender or inner fender. Take off all the nuts from the outside you can get to. One will not be accessable that is between the fender and inner fender. From the inside drill the head off that bolt, I believe its the upper right from the inside. Remove the glove box and duct work on the inside then you can remove the inner box to access the heater core. Replace heater core and reinstall the inner box and duct work. As for the one bolt you drill the head off I don't worry about it the other bolts hold it just fine. I have done this on A bodys with and without AC its alot easier and quicker then pulling the fender. Hope this helps JKaz