This will work in Missouri as well. My car is old enough that it doesn't require any kind of emissions test. I found a gas cap for a 1970, but the cap is too big for my fill tube. I am going to have to drill my cap, I guess, but I don't know for sure where to drill it to allow for the venting, or how big the hole(s) should be. So......... unless I find a different fill tube to use, I'll still need an idea as to where and how big to drill.