All the shops I ran...I made sure had a spiral bound guide book from "Check-Chart Publications" that covered every vehicle manufacturer. This manual covered dry fill and service capacities on engines, transmissions, cooling systems, AC systems, and differentials.
It also covered factory recommended service intervals, lubrication/fluid specifications and had diagrams that showed where every grease zerk was, every drain plug and every fill/inspection plug. Also listed torque specs on lug nuts and oil drain plugs. These books were worth their weight in platinum.
I'm sure they've been discontinued by now since most all of these specs are kept on various software platforms.