"Blue prints" were written and supplied to the engine plants outline pretty much everything connected to how the engines were built, assembled, painted .... until they were ready to ship. Accessories were added at the car assembly plants so we could expect to see some slight differences in some details but there is not allot of wiggle or possibility of varying the process much
My bold. And that's the key here, isn't it?
The engine plant shipped out "base engines". For a 67 289 2v, for instance, that would include (but not be limited to) a 289 2v automatic, a 289 2v stick shift, a 289 2v stick shift T/E and so one. The engine plant couldn't produce too many variations in base engines or the system becomes too unwieldy and expensive.
These engines were shipped without fuel pumps and without any accessories, usually on the nose of the engine. Some areas of the country call this the "front dress."
I'm imagining an assembly plant engine accessory build line where engines are arranged in the same order as the assembly line. Build sheets are consulted and options added to the engines. Some of the options could use original bolts/nuts/washers and, when required, new hardware is used.
It's tough, without your help, to determine which bolts/nuts/washers are re-used and when new bolts/nuts/washers are required.