Need paint number to match this truck color.

[GMC"ER]

I am going with the factory two tone white and blue and I need a paint number to give to my paint guy. I think that this is a factory color that came on the truck my truck has been painted in the past and it shows in spots this color blue but I want it back to original paint colors anybody know what this color name is that is on this long bed truck and a number? I am going to go back with this color scheme on the GMC stepside. Hope the picture with the color that I need is not to small to see good? Thanks for any information. Robert