What book are you referring to for the part numbers?
My book here doesn't have part numbers
He's probably looking at the GM Master Parts Book.
You can download it from The Old Car Manual Project or buy one from Rock Auto or the usual suspects.
Here's the GM interchange parts manual for 1929 - 1959 (Chevy, GMC Truck, Olds, Buick, Pontiac) $19
https://www.rockauto.com/en/catalog/gmc,1950,truck,3.7l+228cid+l6,1440375,literature,part+guide,910