I have a 1982 PXN 10 in white and the frame is very similar to yours with a chromed fork and the newer style simplex drop out that is threaded and has a stop. I know that the older PX 10s from the 70s were sold in black. Looking at the catalogs online, I don't see a black PXN 10 either. Nor do I remember seeing one when working for a Peugeot dealer in the 80s. This may be a European model.

Are you located in the States?