I'm not really all that up on bike terms what is a head set for a Schwinn. I would have thought it was a gasket and head itself, if it were for a motor. Is it the rear cassette or the crank assembly or maybe the goose neck thing on the handlebar assembly if you are talking about a bike.
I think it's just a 1" threaded. Any bicycle shop should be able to get you one. Don't go for the cheap one (like the one on dep store bikes), They are complete crizap. Get the Tange/Sakai for around $20 made in Japan.
Measure the fork tube diameter to make sure. You could also take it w/ you.
Thanks Tyrslider,
I contacted an online bicycle shop about the biycle.
You were right, they said I would need the Tange
1" headset for the old Schwinn. I really didn"t expect
to get an answer from them that quickly....so I will
order from Hiawatha Cyclery.