Seat belt date codes

[Cuda_mark]

I was wondering what the typical date codes would be for a March 1970 build convertible. The MMC guide says that all belts should have tags that match within 30 days (it's a vert so the date codes are quarter based). The one original tag that I have for the car says 1969-3. That seems too early for a March 1970 build though. Does anyone have a build around that date with original seat belts? If so, what are the dates?

[JH27N0B]

As I recall, the seatbelts in my 4/70 SBD T/A were dated 3-69 also.  Seems to be a real common E body seat belt date code.
They must have cranked up the seatbelt factory that day and worked 3 shift filling up a warehouse with 10s of thousands of E seat belts.
I always LMAO seeing experts and pundits giving their profound guidelines on datecodes like it was some sort of exact science. It most certainly is not.
I have worked as an engineer in manufacturing most of my career and am quite familiar with assembly lines and sourcing.  In modern times there is a lot of "just in time" sourcing which means components come in with a very short time window before they get used.  But that is a more recent concept in managing inventory compared to 50+ years ago.
Some parts I am sure they stocked up on and had months of inventory, some were delivered shortly before they were actually used.  Suppliers had their own way of managing their date coded parts inventory.  In some cases for high use components, they might have been cranking them out day after day, month after month.  Other items that weren't as widely used, they would run in batches, make months worth of predicted demand in the same week or even day, then store them in the warehouse and deliver some from time to time as ordered.
Some bins or pallets of of parts get misplaced for a time, and may get sorted out and delivered months after more recently made parts were delivered.
Some parts get sent to engineering or quality control for evaluation or testing, then later unused ones get sent back into inventory to be sent to the customer.
Cars come off the line sometimes with problems and in some cases even missing parts, they get parked in a holding lot until the problem can be rectified by plant mechanics.
So datecodes of parts on a car when it got delivered to the dealer can be all over the place, from many months before the car rolled of the line, to a week before it rolled off the line, or even after it rolled off the line but before it got put on a railcar at the plant to be sent out into distribution.

[EV2RTSE]

Agree with JH27. My car has a 3-70 door sticker and 1969-3 belts also. Hamtramck car with Pontonier belts. I wonder if LA built cars with American Safety belts have similar or different date ranges, accordingly.

[mk]

My 70 E body convertible with a build date early April of 70 has 1969-3 on the tags of all the seat belts ........ will have another to be sure.