Hi,
Goertz mentioned them in his 'Die Pistole 08'. Reinhard Kornmayer has material about them. He mentions about 100 were made, indeed with an N prefix.
They had small parts like the safety lever and the sideplate made out of pot metal.
1001 was the production code designated to the old Haenel plant. It can be found on the infamous DDR magazine tubes and also in the name of the Walther clone they produced under the name Pistole 1001:
From 'Die Kleine Waffenkunde' produced by the DDR Ministry of Interior in 1966.
Interestingly enough, the 1966 DDR weapons manual only mentions the Pistole 08, the Makarov and the Pistole 1001. Nothing at all about the P38. I believe this manual purely mentions those arms on which no other useful data was available at the time.