I've replaced it with this www.carbuilder.com/uk/52kw-car-heater-kit from Car builder solutions. It's slightly larger than the P1 heater so may be about the right size for the aperture on your car. I appreciate you may want to stick with an original unit (if you can find one) but I wanted to go with something that was a bit more efficient.
yea carbuilders are the nuts. I have kept the original outer case and modified the internals and made a "his and hers" lower vents and also a direct out to the bottom of the wing for hot running in traffic
I'm running the original heater box, fed by a 270cfm inline blower, with bespoke ducting to direct air into either footwell. You can feel the breeze at the top of the screen, too! I also have a heater bypass set-up so hot water circulates from the back of the head regardless of the heater valve being closed. The photo shows the initial setting up. It now has silicone hoses and looks much tidier. The motor wiring is on a quick release connector should access be required to the battery for example.
-- Edited by Gary S on Wednesday 26th of February 2020 08:40:38 PM
I've never had the balls to turn my heater off Gary! It's always in the flow. I did do the same bypass idea and also have a header tank tucked up inside the wing which does work well.
I did plumb that in so that the water flowed through it but not that successful so now it just has a feed into the external pipe running alongside the head.