This started as a thread under maintenance I decided to copy it here so more people could look it over, I hope this helps everyone when they need to rebuild or service this box behind the dashboard on 71-73 cars equiped with air conditioning.
Link to my photos of rebuilding a heater A/C box you may have to copy and paste the link to make it work right due to spaces.
http://s1031.photobucket.com/albums/y377/72hcode/Heater Box AC/
Reference this for position of levers...
How to replace your 71-73 Dash Pad.
1. First, obtain your new dash pad from your favorite Mustang parts vendor.
2. Start by removing the original dashboard from the top. Unscrew the six screws aligned across the front of the top and also taking out the three screws above the instrument panel.
3. Continue by taking out three additional screws laid across the top of the passenger side. These are the ones that keep the top of the dashboard in place.
4. Lift the top of the dashboard...
1971 to 1973 fastbacks didn't come out with wind down quarter windows - the only way you could go pillarless was to order the electric window option. However all the holes and mounting points are pressed into the inner rear quarter side wall to allow the winding mechanism from a '71-'73 coupe to be transferred directly into a fastback. Why Ford didn't sell the fastbacks with manual wind down quarters when they were clearly designed to have them fitted is a mystery, but I'm assuming some...