We have a manufactured home with a Coleman furnace. The heat exchanger had to be replaced today because there is a slight crack starting in the ceramic combustion area. I had no idea what the heat exchanger might look like until they asked me if I wanted to keep it. If the picture comes through, you can see why I was interested in it.
I suspect that any HVAC company that does Coleman furnaces would get a few of these every year. For all I know, lots of other furnaces may have heat exchangers of a similar design. At this price (free) one could afford to use it and just throw it away when it gets dirty!!!
I did try to post a photo of this heat exchanger to the yahoo woodgas group, but gave up, as usual, in frustration.
Just not the brightest bulb in the chandelier, I guess.
I sure hope it shows up here.