I bought the full set of GM manuals and the separate electrical diagram book for the model year of the engine package I used. In these books was an illustration and pinout descriptions for the junction block I used. If buying the books isn't a possibility, I'd visit a a local dealership and try to get a printout from them for your junction block.

By the way, the separate electrical diagram book isn't strictly necessary because the individual diagrams can be found scattered throughout the service manual book set. Being scattered makes it more time consuming to get all of the information, so I found it better to have all of the diagrams in one book. I recommend getting the GM electrical diagram book matching the model year of your engine package.

By the way, please don't post scans of diagrams or other copyrighted material from AllData or any other source.

Jim