Is there an easily accessible historical archive of safety standards? While a shop could be expected to have current standards and likely the one before, how many shops have the standards required in 1949? How many owners of modified vehicles (especially second owners) correctly know the year that the pieces were taken from? If I used the once common Jag rear end for a project, isn't it easiest for everyone to declare that the donor part is from the first year it was available? Proving otherwise would be a lot of work.