The recirculating heater does not need anything but a switch so it is fairly easy. The switch looks like this and there are several varieties and colors it is applicable to both heaters.
https://www.flickr.com/photos/advance-design_parts_co/8129352382/in/set-72157631868452754
The Air Flow on the other hand has a few more parts, a Ranco valve, dash bracket, control stalk, and a firewall gasket that goes around the motor. Valves are available rebuilt from some vendors, most of the other hardware will need to be sourced used or NOS. This is what the various parts look like if you look through my photos you can see more views.
https://www.flickr.com/photos/advance-design_parts_co/8129313579/in/set-72157631868452754

1950 Chevrolet 3/4-Ton 3600
More pictures on Flickr