Maybe more than likely the spindle takes a No. 1 Morse taper
and is threaded 3/4-16 in which case you need only get some
catalogs from Crafts Supplies USA and PackardsWoodworks.
This configuration was standard for Craftsman lathes and
there are a load of accessories for it.
Now, if it's threaded any different, well...
CRAFT SUPPLIES USA
Contact: Darrel Nish
Address: 1287 E 1120 S, Provo, UT 84606
Email: firstname.lastname@example.org Web Site: craftusa.com
Contact: Brad Packard
Address: 646 N Trade St, Tryon, NC 28782
Phone: 828-859 6762 800-683-8876 Fax: 828-859-5551
Email: email@example.com Web Site: packardwoodworks.com