Yes, it's the standard US camouflage. I used the F-4Dablemodels decal
sheet for my 1/72 model and it shows a pretty clear demarcation between the 2 greys.
Some airframes even have a third shade on the nose cone.
I live in Switzerland and I've been around those jets a few times, If you need some
reference pics I can email you a few. Here a pic of my model:
And the decal instructions:
Cheers,
Jesús.