Printer ribbons

[Ian King]

When I acquired my PDP-11/34, I also received a Centronics 503 printer, along with an entire case of ribbons for said printer.  They have a part number of 63002293-5001.  It's a black nylon ribbon on two spools.  These are NOS.  I haven't been able to identify anything that uses them - and I mean anything, because I can't find anything on the Web about the Centronics 503, either.

Does anyone have any leads on this?  I'd like to find that these ribbons are worth something to someone, because I'll never use more than a few in my lifetime but I don't want to just trash them.  Thanks -- Ian