<VV> 69 headrests

[cfm]

hey, I have been trying to sell some headrests and I had a guy ask me about a date code on the chrome stem. I never knew this. So I went sleuthing in my garage and I have this extra 69 500 bench seat (for sale btw) laying around I it had the rounded head rest, date codes matched between the two, but I know little about the car it came from. The 69 monza coupe, has the more conventional straight style, has two and I checked those and those codes they matched. Then I checked my convertible and it does not have a matching number. And the extra set I have that I bought for replacement do match. Some have physically embossed stamped, yet one has more of a inking style stamp on them.
So the questions are:
1.) is it important?
2.) are the dates to match, or were the fisher guys just yanking crap off the shelf and sticking it on the cars? (derogatory tone not intended)
learning something new everyday...
-chris