If you don't know how it goes together or the adjustment then I strongly recommend buying three books. First is the Fisher Body Repair manual, a book that gave body shop techs the info as to parts numbers and adjustment procedures to repair wrecked cars back when they were new and since they were new no one knew how to do it without a reference manual.
Second most important book is the Assembly manual. It told the workers on the line how to build a car out of a train load of parts. Once again it lists all of the part numbers (now all obsolete, but useful as a reference to identify a part) the torque value of any bolts, and listed any other glue or chemical needed to put that sub assembly in the car.
Finally of interest to the line tech that fixed the cars under warranty would be the Service Repair manual or the Chassis Service Repair manual. If you are not a mechanic the words Remove and Replace (R&R) probably are not going to be of much help, But this book lists the procedures to fix most wearing parts on the car and to overhaul the Tranny, motor, or rear end as needed. Probably a better reference if you have limited mechanical experience is a Chiltons Repair manual or a Motor's repair manual from 1966 through about 1968. These manuals were well illustrated and walked you through the R&R procedure a step at a time. What they do not have is the torque values (listed in the Service manual or the Assembly manual).
All of these paper books are available from time to time on line as former mechanics die off and the estate sale puts them back into circulation. You can find a lot of the GM manuals scanned on a flat bed scanner and burned onto a CD. They are not as easy to read as the originals and it requires you to print the pages to be able to use them in your garage. But if a hard bound book is unavailable it is often your only other choice.