A long time ago I read performance numbers through 90-95 and what struck me was the weights. You always read how heavy the later years are. Did a search and found it, was Jim Ingle?s text.
https://www.corvetteactioncenter.com/tech/perform.html
Even if fluids are not down to the ounce, calibration of the scale and what ever, engineers have an mind setting for keeping them "good enough " for what they presenting. Anybody else put different year cars on a scale?
Thomas