I fitted an original Series 2 heater to Fenchurch last night. It was a rather more awkward job than I expected due to lack of space inside the dashboard for ducts and pipes. The demister outlets are a bit feeble, particularly the driver's side one (I suspect the vent is partially blocked), but it does work. How well it works depends on how hot the engine is, and in this weather the engine has only reached about 60-70C by the time I arrive at the office in the morning. It doesn't even really start to warm up for the first five minutes because I live at the top of a big hill (actually the side of valley) and mostly coast down it. I may need to think about fitting a radiator muff so it warms up faster.