If the drawing prints to PostScript, can you save to PostScript, then open in Adobe illustrator or Canvas and export as DXF / DWG ?

I'll post to my own reply since it's been up for several hours and i don't want to revision-historian edit it.

Well, the product is prnprint, and it won't print to pdf, and it only prints to printers windows knows about, such as physically- or network-attached printers; ms xps document writer; ms office document image writer.

I tried changing the .prn extension of a legacy drawing file to .ps and .pdf and to .dwg to see what would happen. Acrobat and AutoCAD didn't accept them as valid files.

I'm starting to think it's a pointless exercise trying to go in the reverse, and that it's likely that the image printed to printer is a processed flat shot of the rendered screen view. So, without the original it seems the prnprint output to paper would likely need to be scanned, attached/imported to a CAD app, traced, and adjusted to scale, then extruded where necessary and then further manipulated in 2D/3D until the attached scan is no longer needed. Hopefully, we won't need to do this, as it would be very time consuming (though having traced scans might save time if any tracing is faithful or within tolerances and still manufacturable.

I believe so. However, in our case, we received from a party on the same project a file that is assumed to be part of an archive of a massive amount of drawings that for some reason archived to just .prn rather than additionallly to their native or a compatible formate. If they had thought to save as .dwg (well, then again, this supposedly happened years ago, which might mean even if they chose to and were able to dump to .dwg, there might have been lost properties in some of the 3D files... i assume), we would have an easier time. At this point, i can't/won't spend any more company time on chasing the problem. The engineer with the drawing can read the details (with a magnifying glass, since our old plotter is not ps capable) on 11x17...