Now all parts are delivered except for item 11 (top picture) and I can answer my own question. Yes the D4 Airtronic does fit the brackets.
The missing item is just a thick rubber washer which I have a quantity of in my garage if only I could find them!
Moral of story with buying parts is to go to MAN not VW, these items were
almost half the price from MAN than I was quoted from VW!
I've investigated the fitment of this assembly to the chassis of the vehicle and see that it all hangs from four either large self tapping bolts or maybe Rivnuts & setscrews, there are simply four holes at present which line up with the holes in the bracket which are for 6mm setscrews or self tappers. My aim is to fit Rivnuts in the chassis.
The ingoing air duct on the heater is 75mm diameter which, as far as I can ascertain is the same as the factory fitment that connects to the drivers door step so now a decision on either purchasing that at £100 plus or using flexible duct (which I have in stock) and a round fitment in the door step side.
The outgoing heated air outlet on my heater is the straight 90mm version, that cap is interchangeable with
others that are commonly available. Current thoughts are to split the output beyond the heater and feed one up under the driver's seat and point rearwards. The other to extend back along the chassis and bring up under the rear seat with its outlet pointing towards the bed area.
I already have a Truma 4e (gas) mounted under the rear seat, the Eberspacher is to provide an alternative fuelled heating source.
Watch this space for progress as it happens!