I have a buddy (not online) who is converting from a 1969 small block heater core to a new big block system including the "box". He has been told that to do this job he needs to remove the fender! Surely it can't be true. Is this not just a miserable under-the-dash adventure? Any hints and tips I can pass on? I am sure that a few of you out there have made this repair and maybe even conversion. Thx in advance.

The far right side of the blower box is under the fender. He will have to remove the fender to get to that side of the blower box. As for the conversion, it has been covered many times. Do a search on this topic.

You don't have to even remove the outer heater duct in the engine compartment. All you need to do is drill two holes in the center of it to match the big block heater core tubes. The duct itself is the same, the big block ones just have the holes cut in them to match the heater core tubes.

You need to pull the inner heater duct to replace the small block core with the big block one though. The inner box itself is also the same but the core is different. No, you can't turn a SB one over and put it in backwards. When you replace the inner box there is a foam gasket available that blocks off the holes in the firewall where the SB heater tubes were originally.

Buy the big block heater conversion kit most of the parts places sell. It's a plate that has the two holes already in it. You just need to affix it to the duct in the engine compartment and cut out a matching hole under it.

did the factory block these SB holes off....did the plug look like these? Name that pic :D

PIC 1 http://hobbystage.net/camaro/media.cgi?site=electronic2&folder=*&id=1113095460-006219

PIC 2 http://hobbystage.net/camaro/media.cgi?site=electronic2&folder=*&id=1113095415-006218