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thank you for this update
pillar size - your measurement of 26mm tells us it is likely either 26.2 or 26.4mm actual size, this would tend to suggest it is constructed of a quality plain gauge tube set such as Reynolds 531 plain gauge, Accles & Pollock or Truwell
yes, the Sachs items are very much later than the cycle
you may be able to find a date on them
they began date marking their products in 1978 with a four digit numeric code
the first two digits refer to the week within the year of manufacture and the second two to the year:
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