When I was involved in the world of Saabs, I was able to get my hands on the parts catalog software they used in the dealers to look up parts, exploded diagrams, etc. Same software as on the computers at the dealer's parts counter. Actually wasn't that difficult to find, it's all over the internet. Made a WORLD of difference when I was able to look up parts and diagrams at home, then just go to the dealer with the list of parts I needed.

Is it possible to get the same thing for GM or Chevrolet? Yes, I know the computers aren't running Windows (at least they weren't the last time I checked at a dealer), ISTR them running Solaris which I happen to have a computer running right now on my desk

You can find a pdf of the 4th gen parts book here.

not quite as handy as having the program on the computer, but will still fill the need. Thanks!

That's all you are going to find.