New Street Demon carbs

I have one on the 351M in my 75 F250 and love it. I snagged it used off Ebay needin some repair and fixed it, put a kit in it and it's been great. I had an Edelbrock 1406 on it that ran really good, but I wanted to try a Street Demon. I couldn't afford a new one so I looked on Ebay for months and found one. The secondary air door spring was MISSING when I got it. A Thermoquad spring fits right in and works great. There's NO mistaking when that secondary barrel opens up. lol