camshaft timing marks
timing marks on 1995 Audi A6 Quattro
there are no marks on the cam gears. the two diamond shape plates on the front of the cams have a large and small hole in them. there is a special tool (long bar with pins) that lines up these holes. the bolts on the cams get loosened and the gears "poped" free on the cams so they cam spin free while setting belt tension. the cam gears are conic and not keyed to the cams, only the diamond plates are keyed to the cams.
I strongly suggest you get a repair manual for this vehicle if your going to be doing your own work. You can get an online subscription to the information you need here: