Paul,
          Did read on this forum about someone who used
the cooling tube from the muffler to heat the cab. I am
currently trying to see if I can get rid of my cab water
heater which is really quite heavy when the water is added.
So I can either take heated air from the muffler area which
I do not like due to the possibility of CO gas, or somehow
get hot air from the rad exit.  Does anyone have
experience / advice on this matter ??
                            Neil.