FYI the Osborne manuals include only one version of each drawing, and often there were several revisions. My understanding from Jeff is that they generally picked the best copy, and sometimes even the best was poor. I would expect that the best and/or only copy would tend to be the last revision rather than earlier ones.
For example, for the 1967 manual you see the two piece fuel line with extra guarding, nothing like my Dec 66 build one piece line that runs along the driveshaft.
The drawing revision history is illegible to me, so we can't correlate the drawing revision date with the build date. There would also undoubtedly be a time lag between when the drawing is signed off to when it is in production. I can see someone making a call to deplete inventory of old stuff unless specifically instructed otherwise or if the instructions were unclear.