UBB.threads Forums Edged Weapons European Edged Weapons DDR Dress Dagger.

The only way to be sure is to just acquire the ones that were maker-marked in the 60's-70's.
From the time the daggers became an issued article from the armed forces (in 1975), there is almost no way to tell if it is made in 1985 or 1995..
Only provenance can tell.
I have read somewhere that the serial numbers on the daggers where going up to about 5000-5500 before the nation collapsed, and only presentation daggers could have numbers above 6000. However I dont know if this information is trustworthy.