For those who would like to convert GMC part numbers to various vendor part numbers, there is a listing on eBay: item number 184230293265. I wish there was one for Eagles. :'(
Trouble is with those is that there were many produced over the years, updating the previous part numbers. Several times we would go through three or more volumes with the part number changing only to finally find the new part number was then discontinued. Still, they sometimes may be of help. Would be the best to have the whole series of manuals till the last produced though. Knowing who manufactured a part for GM was useful at times tracking down an item.
We have one similar to that one ln the link and also another about 15 years newer & 3 times as thick. Yes some numbers go through supersessions others never change while some go into unobtainium but through the years the manuals have come in real handy giving newer replacement part numbers or converting to other vendor part numbers. We also have an original early 1980s GMC parts price list manual & that one would have you crying a lot to see where prices used to be...