My
...
There were two patterns for most vehicles using the 383 scheme.
The early pattern is in the left diagram posted by Militaryguy.
The pattern was later refined to the "wiggly line" style and more precise amount of area covered by each colour (45% green, 45% black, 10% brown) as in the pattern posted on the right.
Thus, if you were repainting just a section of a vehicle wearing the 'old' pattern, you would use that one. However, if you were repainting the entire vehicle, you would bring it up to the 'new' standard.
Some vehicles, like the M151, were being phased out before the new pattern came about, so they didn't get one drawn up for them.
Cheers