I was putting a Voyager rack on the back of my 81 World Tourist, and I noticed a small white paper sticker on the left dropout. It says Schwinn approved Giant. So we at least know the origin of one frame. It has a made in Taiwan decal on it, so would it be a leap to suppose any Taiwan labeled Schwinn came from Giant?

I think it's a good possibility. I've been under the impression that the Japanese-made Schwinns are from Panasonic, and the Taiwan-made Schwinns are from Giant. I've also heard that the Giant-made Schwinns have serial numbers starting with G. And there was a suggestion not long ago here that there may have been some Schwinns built by Bridgestone, in Japan, so maybe not all Japanese-made Scwhinns were made by Panasonic......Also, Japanese companies, Centurion and Shogun to name a couple, moved their production to Taiwan by the late '80's or early '90's for economic reasons, so it might not be as simple as saying all Taiwan-built Schwinns are from Giant, because by the late '80's, more and more bikes from a lot of companies were coming from Taiwan. I don't know if any Panasonics were built in Taiwan, for example. Scooper, Bob Hufford, or Sierra will undoubtedly know more. It's a good question, though.

I don't believe it would be a leap; as far as I know there were no Taiwanese sources other than Giant. Japanese sources were Bridgestone and Panasonic. Chinese source was China Bicycles Company of Hong Kong and Shenzhen.

By 1986, Giant was producing about 700,000 bikes a year for Schwinn - more than 80% of Schwinn's product.

EDIT- well biked, you beat me to it.

Heck, I should have just not posted and waited for you. My stuff was guesses and conjecture. You got right to the point with facts.