Reply to Old Magnet:
No different shade of yellow that I know of.....standard Highway Yellow from 1931-1979.
I just bought some paint for my D2 and found that PPG has 4 different colors for Cat yellow. I went with the 80979 because it was the brightest, and it matched what I saw when I stripped the old paint from my engine.
The 80021 seemed closer to the "Old cat yellow" I bought from CAT about 12 years ago. I think I saw date ranges for the application years, but don't quote me on it.
Caterpillar Highway yellow----------------------------80979 Up to ~1950
Caterpillar Yellow (old - replaced by 80979)-----------80021 1950 -1979
Caterpillar Yellow------------------------------------81985 Beige type yellow
Caterpillar Yellow------------------------------------82454 Orangy yellow
Caterpillar Yellow------------------------------------83930
Anyway, I was just surprised at the color difference between the Highway and the Old yellow. Something to think about if you are considering a resto. Not sure if any of these are right. :confused2: