Part # is 5843802, heaters come as a kit, vents, ducts, switch, hardware and heater. Here is my NOS GMC Recirculating heater you can also see in the picture series in this set an Air-Flow I owned some years ago as well (USA models).
https://www.flickr.com/photos/advance-design_parts_co/8129332002/in/album-72157631868452754/