In the Army, as far as I have encountered, nothing is solid 383 green. Everything in nato 3 color or 686 tan. 686 acctually varies depending on manufacture of paint.
From what I can see, there are two shades of "Tan". One is a "Swiss Coffe" color of tan, while the other is more of a "Sand" color.
I used real 686 Sherwin Williams tan on my 1008 and it is more of a sand color.
Both are correct as I have seen both side by side at our armories and in the field. Also, the application of black accessories has become very standard. Lots of mirror brackes and light housings etc are now coming black instead of green. On HMMWVs you will see some with black radiator grills and others tan, wheels will vary from black to tan as well depending on who painted them. Also, it seems that many times the brush guard across the front grill is still green or black while the vehicle is tan. THey hinge it down to paint the HMMWV and then are done and clean up and go oops we forgot to paint the brush guard, oh well.
I THINK, the Marines use solid 383 green on their vehicles. Its been a while since I was on an OP with them, but that sticks in my mind.