Generic dimensions for single DIN are 50mm high and 180mm wide with depth varying by manufacturer. The publications you're looking for from DIN (Deutsches Institut fur Normung) are:
BS AU 207 - Specification for dimensions of car radio installation space
ISO 7736 - Road vehicles; Car radio for front installation; Installation space including connections
These publications are from
http://www2.din.de/index.php?lang=en but cost money. I'm still looking for free sources.