I afraid i won't be able to help you. I'm not sure that the yelllow on your picture comes from Porsche.... My opinion is that it's a personnal yellow, made by a specialist....
The only thing I can do for you is to give the codes (is it english?

) i have in my books.
So, I'll only give the ones between 1974 and 1989, I think it will be enough. Sorry, it's in french!!! "jaune" means Yellow.
1974/1975 :
117 : Jaune clair
1976/1977 :
106 : Jaune Talbot (I think it's the color of Steve Marshall's 911's)
117 : Jaune clair
1978/1979/1980 :
106 : Jaune Talbot
1981/=>1986 :
None
1987=>1989 :
10W : Yellow lemon.
That's all I can do. I you think this color is younger, ask me for more codes, but I think it's not a Porsche standard color.
I hope you can understand my bad english!