You're gonna be hard pressed to find a clevis still made in the USA.
Warn's have a China stamp on them.
Look for Crosby if you are looking for excellent quality "Made in the U.S.A." rigging. I work in the hoist and crane business, we use their products daily, and it is top notch stuff.
http://www.thecrosbygroup.com/default.aspx?
Master-Pull has some really sweet shackles, not made in the USA but they are very high quality.
-Alex