There's several different combinations, perhaps their kit was a generic set to cover most and not use whatever was left. But that still sees 5,6 and 7 as common amounts per side, and still not enough if you were trying to replace a broken stud with a bolt, in case someone tried that. On other engines the locking tabs went on the outer-most bolts and bent over the side, not sure as to what these models used originally. There's possibly diagrams in the manuals, assume you've already looked.
Just looked at 76 manual for something else, it shows that the downpipe collector that uses 3 studs could also use 2 studs and 1 bolt when the vacuum valve was not used in between, so things like that would perhaps see an extra bolt or 2 thrown in.
