Reply to chugwater crawlers:
Caterpillar calls it "Hiway Yellow". Most dealers can still get it for you.
The yellow that the Cat dealers use today is a darker shade than Hiway yellow.
Most automotive paint shops will give you a fairly good match to the original yellow.I painted my 933 into a mustard yellow that Cat used for a few years.
I don't know in the USA ,but in Europe, very soon there will be new regulations regarding paint in the UK,lead paint was banned some years ago but now it seems that water based paints will be the future.I find the older paint resists fading and weather much better. But the two pack paint is also good for standing up to weather.
Martyn