www.factorymanuals.com I found this link on a post here, thanks to somebody I shold have remembered.. For older cars and trucks you can buy a used real shop manual for about what one of those Chiltons or Hayes from the parts storee costs. I feel theshop manuals are much better. The less you know, the better book you need.
Helms of course is where the GM Owner's Manual points you. I am not sure how far back they go. In the mean time, their price for a new manual for my 02 Cavalier is $120. Likely I will give up and pay it when I have to. For now I am enjoying not having to do much on a relatively new car except change the oil. I found the oil filter in less than an hour without the book.
Another source for older manuals is http://www.automanuals.com/. I have not bought anything from them and can't say much about them. I am sorry I got my original link wrong. Fortunately jer found the right one, http://www.factoryautomanuals.com