Totally off-topic, but today I helped my mate dismantle the dash of the parts donor Citroen XM on the driveway.
The sheer amount of copper behind there is staggering, so much cabling..
Anyway, what follows might not be news to some, but I'm putting it here in case someone finds it helpful.
Got the heater unit out of it, and interestingly enough it's almost an exact copy of the one in the rangey. The only real difference is that the XM unit is slightly more pauper spec, in that it doesn't have provision for separate heating zones (independent left/right flap control). The independent flaps are there, but bound together, most likely with the same type of metal rod that the rangey one uses for the top flaps.
As this XM is itself a semi-pauper spec one, with no air-con, it only has a single blend motor, used to control the temperature (this is digital on the XM). The distribution and recirculation flaps are cable driven.
Blend motor is an exact match for those in the Rangey, and unlike ours, it has a ~ 15cm pigtail before it hits a connector. Why they didn't do that on ours, who knows.
The heater unit itself is, as mentioned, very similar to the Range Rover one. The only real difference I have been able to spot is the lack of zone control. There are mounting posts for a blend motor on the drivers side, but the hole for the lever is missing, and a bit of plastic moulding in the same area is missing too. Wouldn't be too hard for someone enterprising to modify though.