I just removed the smog from my 66
Hi. I just did this to my 66 200ci today and it worked great!
What you need are 1/2 inch set screws, either 5/8 or 1/2 long, with a fine thread and a hex head. Put some Loctite on them and your done.
I tried looking for the brass fittings but I couldn't find them and according to my local mustang shop I didn't need them. The set screws worked perfectly.
You will probably need to go to one of your smaller neighborhood hardware stores to find them. I got them at our local True Value hardware. I could not find them at any of the larger home improvement stores, Home Depot, Lowes, etc.