I know A-headset made them for standard(you know, old Schwinn size) about 2007 or so. I have one on one of my bikes but don't want to pull it apart to get the part #.
I have done, as stated before, and just filed the threads off a standard threaded headset and used a cap/bolt/star nut to convert them to threadless. I've have had one on my bike for about 2 years and haven't had a single problem with it yet. The only 1" threadless I can get around here are the 1" for road bikes which are 1/16" smaller than the old 1". :roll: