Kuno:
The Zvezda kit is quite OK, I sell them in my shop.
You can try
www.rkkaww2.armchairgeneral.com for a lot of info on Russian trucks including the AA Gaz. Also Google GazAA and you will find a lot of images plus links to other Russian vehicle sites, Google both the net and images.
I am at a HobbyTown convention and 2,500 km away from my reference material but I will be home Monday night and try to post some more info then.
Bill