The way I remember it, a VIN [Vehicle Identity Number] is an internationally agreed format number[?] of seventeen alpha & numeric characters that encodes some details of the vehicle, including it's country of manufacture amongst other things. They did not come into use untill long after Datsun 1200 production had ended.

The numbers that are quoted on our little Datsuns are serial numbers, chassis numbers or body numbers, but they are not VIN's.
My Datsun 1200 parts book calls them "Car Number's"
In right drive models there is a "Type Plate [Car Number Plate]" affixed to the "Hood Ledge" [inner mudguard] & this plate lists the
Engine Capacity
Max HP at RPM
Wheel Base
Engine No.
Car Number
This car number should match the number on the firewall & the plate shows the number of the engine originally fitted to the chassis, so this is how they get the "matching numbers" info

Each model had it's own block of numbers, so there is no real linear string of numbers through the whole model range. By way of example, what follows is just for the right drive models.

Datsun 1200 Four Door sedan Standard & Deluxe. Also Two Door sedan, Standard & Deluxe
From Ser. No. B110- 247,023 From- Apr '71 [Z]
From Ser. No. B110- 341,001 From- Jan '72 [Z]
From Ser. No. B110- 655,001 From- Jan '72 [N]

Datsun 1200 Coupe
From Ser. No. KB110- 877,228 From- Apr '71 [F]
From Ser. No. KB110- 940.001 From- Jan '72 [F]

Datsun 1200 Van Standard & Deluxe [The picture shows a Four Door station wagon]
From Ser. No VB110- 170,001 From Jan '72 [N]
What do the [Z] [F] & [N] mean. I don't know,...... yet.

The ute is a commercial model, or truck, so is not listed in a passenger model parts book & it's my guess that the two door van is in the same category.

Thats all there is in my right drive parts book which is the "revised, December 1973" version.
Note how 'car numbers' seem to be allocated in "blocks', particularly when they start with a number that ends in xxx,001. There is obviously a gap between the last number of the previous model & the first number of the next model, but we have no way of discovering the last number actually used in any allocated block of numbers.

Again, by way of example, the first number allocated for the April '71 coupes is 877,228 while the first number for the January '72 coupes is 940,001 suggesting a production run of 62,772 units, but it would be too much to suggest that they actually made exactly that many so that the new model for '72 would 'conveniently' begin on a number that ends with a xxx,001.

The only way to check on the relative "oldness" of a 1200 is by reference to published production data that lists the relevant 'car numbers'