"Truck factor" was popular in some circles many years ago. Given the number of replies that say that they have never heard of "Truck factor", I'm guessing that

"Truck factor" was popular in some circles many years ago. Given the number of replies that say that they have never heard of "Truck factor", I'm guessing that google won't help me out here. I certainly heard the term "truck factor" long before "bus factor". My understanding of the reason it changed to "bus" was that people in the UK (who use the term "lorry" for what North Americans call a "truck") found the term awkward. That's purely anecdotal, though. It's entirely possible I was in a bubble of "truck factor" usage.