[Adrian Worman]

I have used these codes loads of times now, but I'm interested to know why it was put into place , what specific reasons do the factory's have for using a code like this

[dave-r]

Most parts on the car didn't use the 10,000 day calendar. So I don't know why they would use it on the engine blocks (not all) and auto transmission case.

Many parts in the engine bay used another type of 4-digit code. Where the first digit was the year and the last three the day of that year. Stuff like the carbs, wiper motors, master cylinders etc. I think they call this the "Julian" date.

Other parts such as horns, coil, distributor, used a three digit week of year/year.

Then the glass (sometimes the wheels) used month/year code of 3 digits (Jan to Sept (+ two digit year) and 4 digits (Oct - Dec + Year).

Some bits had an Alpha code for the month (A-M) followed by a single year digit. Carter carb parts, oil and temp senders, etc)

Exhaust and intake manifolds (plus manual transmissions) had a straight forward Month/Day/Year code.

Most engine pads and some wheels have a Month/Day code.