The gas fired jobbies are a challenge to install, but it has been done to good effect. Other Folks here can tell you all about how that goes. And they will air fry your tootsies, or other parts too close to the source. I have heater boxes on my 2332/Sidewinder lash up, and they work -- not great, but they work. Warm to slightly hot air comes out. Takes the chill off. Trouble is, side curtains do not allow much of that warm air to stay around. If you really drive in cold weather and want to be warm, then do three other things: dress appropriately, like you were going to go skiing; carry a blanket; and install heated seats. I have heated seats and several really warm jackets, and gloves.