I’ve got a c. 1950 Delta 14″ drill press. I need a new chuck for it, but the spindle has a 1/2″ left hand thread.  Can someone direct me to a source or at least some specifications so I can do a more effective search.  I haven’t turned up anything so far.

I have two other spindles – a morse taper and one for holding mortising chisel bits.  I’ve seen chucks for a morse taper, but these seem to be for lathes.  The mortiser works like crazy.  I’m using it now to make sashes for storm windows.