Finding out the exact build date of a car?

We are trying to find a car with a matching birthday. Does any know what cars in the early 70's provided the actual day it was built? 

What brands do that? 

Thanks!

JM

This feels like a canoe.  But I noticed new F150s have the build date stamped on the back of the bed under the tailgate.

Door jamb stickers on many cars include the month and year.  Some include the date that the car was originated, so it would be a few days after that it was actually built.  When I say originated, someone in an office received orders to build an [insert vehicle] with A/C, FM radio, blue paint, and cloth seats so they send that spec sheet to the factory where it is built in the coming days.

Early GMs had this spec sheet stuffed between the springs and padding of the front seat.

You might have to settle for a range of dates.  Many cars take a few days to assemble, so do you want the origin date?  The date it rolled off the line?  The date it was placed in lot inventory?

Manufacturing is a bit convoluted.  There is the origin date (when someone specs out the car they want to build), the beginning of physically producing it (someone grabs a frame and puts it on the assembly line), the date it rolls off the line, then the lot inventory date.  Basically (for inventory purposes), there is that origin date, then that piece of paper goes into a big building where magic happens for a week or so, then cars get spit out the back end.  Then someone goes through over the next few days and inventories the factory lot to match VINs to Origin cards and THEN it's actually "built."  It doesn't really exist on paper until a certain number of days when it gets inventoried.

Finding an actual date that it "rolled off the assembly line" might be difficult with a 70s vehicle.  Today, it's easy.  They scan everything and each part is tracked electronically, but in the 70s, it was all paper and humans.

I like to think my REPU, and I were "made" the same day. It's possible. It has a March 1974 manufacture date on the tag, and my birthday is in December of 1974. I'm weird, I know this.

For all of the British Leyland stuff you can get a "Heritage Certificate" which frequently has the order date and the dispatch date. This is available from the "British Motor Trust".  

You may be able to find out through one of the heritage or historical records companies. Some have much better records than others. They are typically $20-$40 per vehicle though and usually are not fast.