Updated paint code

hi everyone I have a 66 Plymouth valiant that’s a light mist blue colour that I am having painted. My problem is when I take the paint code to the paint supplier they say they can’t help me I even went to a dealer body shop and same thing. So my question is has anybody here run into this problem or is there a place to enter my code and get a new code the paint shop can use. Thanks
Do you have a spot of the original paint left on the car like underside of the hood or trunk lid? The paint companies can scan it with their gun and get you what you need. If not hopefully someone her has the same color and can come up with a code for you.