I have a gas heater in my '71 that looks like a factory installation, 
but I can't find a manufacturer's name or model # anywhere, so I'm 
not exactly sure what I have.  It's a grey clyinder about 15" - 
18" long, and 6" in diameter with a piece of sheet metal 
across the top that looks to have a reddish orange switch or 
somthing on it.  There is no thermostat; I just have the 
"Temp" knob on the dash.  The heater is mounted inside the 
engine compartment, and it vents to the passenger compartment.  It 
does not have it's own fuel pump (gets fuel from a T connector from 
the engine fuel pump), and I'm not aware of any coil to give it spark. 
It looks entirely self contained.  

My questions are:

A)  What do I have???

B)  Is there any way to adjust the temperature?

C)  What is the little orange switch/knob for?

Thanks for any responses/help on this.  I really appreciate the help!

Shaun