Ernie, you never cease to impress, sir! - now if I can find some photos....
EDIT: Wait; why is the document giving the part number for RSR injectors under the 85L tank heading?
http://www.early911sregistry.org/for...1&d=1487522629
The more I think about it, short of any photo evidence to the contrary I'm leaning toward the opinion that the claim that the plastic 85L "RS" tank was installed in '74 3.0RS is an error in the Snodgrass book.. Every photograph I can find shows the standard 74-on steel tank, which I suspect is also being referred to by Porsche as "85-liter" (albeit actually 80) at the time?