Richard,
Have a look through your photos, or JB's
, or mine
, and see if you have any shots of the hoppers that show the car side lettering. That would of course presume it wasn't covered in grafitti
. Often times the paint spec is called out on the car side, and sometimes you can go to the coating manufacturer's website and find the specific mix. It won't be RAL, presumably, although I suppose the paint company can serve the European market even if the prototypes are US stock.
Something like this.....
There's no guarantee that you will find the color specification for every car, but I know that I have looked up some of them and found railroad specific colors called out by there system numbers. By the way, a quick look at the Williams Hayward site shows that they do include RAL system numbers.
I don't have time at the moment, but I will have a look around the computer later today and see if I can find downloaded information. I normally download anything I ever come across, because it will usually disappear from the web at some point. Or it will get hidden behind a customer login or some other effort clearly designed specifically to thwart model railroaders from finding out what they have a right to know!
If that method fails, then take a photo of the grey you desire to the paint shop and ask them to match it.
I'll follow up later if I can dig out any other specific information.
Jim