Hi everyone,
I have recently managed to set up the correct ride height (was too high in the front) in my Vectra B Caravan with Astra G springs. To do this I had to made a research of the available factory springs, and I'd like to share the results: https://drive.google.com/open?id=0BzkEdLdAaeNaYjZzZXd6T20tSlE
Maybe someone else will also find it useful.
The equipped springs for the different models:
http://www.partsbase.org/opel/vectra-b-1996-2002-11-front-axle-and-suspension/
http://www.partsbase.org/opel/astra-g-zafira-a-1998-2009-11-front-axle-and-suspension/