No original factory production records are known to have survived the company closure, and this is where the problem originates.
Unlike other manufacturers which can supply detailed certificates on each vehicle they have made, no details exist for the cars produced by BMC Australia.
There is however limited information available through other sources, and these have been compiled into a new resource dedicated to vehicle dates.
While it still is not possible to know the exact date that a vehicle was made, it is possible to obtain an approximate date from a range of known numbers. It is also an option to date a car or parts using stampings on parts or window glass.
A collection of known resources have been compiled on a newly published Vehicle Dates page, including details on components, window glass, and period publications.
See Vehicle Dates to learn about and identifying a date for when you 850 was made.