Thanks, that is helpful. I am stuck with the 2.5TD engine as that's what the S3 came with. Unfortunately the heater matrix is the original S3 one, not the one for the 2.5TD, which is why I can't see how to connect and control it. Are you saying I need to buy the 2.5TD heater matrix and then...

I am restoring a 1983 Series 3. It has been supplied to me incomplete with a 1986-ish 2.5 litre Turbo Diesel engine. Has anyone else done this conversion? Any advice about things to watch out for? The particular issue I have at the moment is how to get the heater working. Clearly the heater...