Does anyone know what settings should I use to get the ffallout 3 green.Obviously it's not the same shade

Fallout 3 green is (1000 point scale); B 452; G 952; R 319

In the Fallout4Prefs.ini you can manually modify the settings (since the in-game screen is not precise/no labeling).

[Pipboy]

fPipboyEffectColorB=0.452
fPipboyEffectColorG=0.952
fPipboyEffectColorR=0.319

This uses a 1000 point scale (0.000 to 1.000)

[Interface]

iHUDColorB=115
iHUDColorG=243
iHUDColorR=81

This uses a 256 point scale (0 to 255)

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Obviously, I didn't modify everything, but stuff under [VATS] is a 1000 point scale so you just need to use the same figures as the Pipboy.

If you are on a console, then I can make a screenshot, but it will be difficult to get the right color.

It would be great if you could make a screnshot

https://drive.google.com/open?id=0B2XtdiP5XzYjeW1aQS1VRTRkSXc

Default for comparison:

https://drive.google.com/open?id=0B2XtdiP5XzYjSjM1NU5HRWIwSk0

Thanks mate

No problem. Good luck entering it via in-game.