Napa doesn't sell premixed paint. They are like any other automotive paint supplier. You will need a current paint code for them to mix the paint. One problem you are going to have is a lot of paint codes floating around on the internet are obsolete paint codes for alkyd enamel. If you don't need a perfect authenic paint match you could make a sample with rattle can paint from tractor supply and they can computer match it. You might also check out this web site to see if Ford Tractor Blue is the corect color. http://paintref.com/cgi-bin/colorcodedisplay.cgi?manuf=Ford&model=Tractor
I believe most Napa stores sell Dupont paint so I would look for a Dupont code.