500cubes, i am in the same boat as you being without a fender tag.
I've been on research as well on what is original and what is not.
The layout should follow alphabetical and numerical order. (apart from the 2 bottom lines which have a fixed style)
Paint and interior layout also is a bit off i think, mostly repeats the colour (F8 F8), gives the interior trim level, style and colour (P6X) and a colour code for the interior door frames (X9). You also mentioned a vinyl top which causes even more confusion for me.
Don't know where you find your build date and order number from?
Don't recall ever seeing the Y05 (US build specs) on a tag, guess this is more of a "standard" that not will be mentioned on a tag.
The Sales Bank (Y16) or Special Order (Y39) are more common to be mentioned on the tag as this is "off standard" and the production line had to pay a bit more attention in such cases
Many enthusiasts have a record of all fender tags they ever came across, then you have like a database of all build dates, order numbers and sequence numbers together.
With that list you can get a better view on other tags if the #'s listed "match" your collected data as they roughly line up, but also this is not a guarantee as there are always exceptions of the rule...specially in Mopar land.
Order numbers, sequence numbers and build dates do not stack up in sequence due to various reasons, but in general you can get a rough estimate if you keep a list of them.
R11 S77 S81 END
A62 B51 C21 J25 M46 N96
R6 R6 P6X X9 A04 030883
E86 D32 WS23 L9E 112164
This is of my car and how far i've came.
The color coding i found during disassembling parts and came across the red R6 colour after removing the brake booster base plate for example.
My build date code A04 is a very close guess, due to some additional info from another member here who could pinpoint it by using data of other fender tags and found a sequence number just below and just above mine.
Order number will never be traceable without a build sheet, but also a tight guess here.
Other then that i did my checks and found it legit, other things are not and will not keep them as a record of being original.
For example, my car did originally come with a 22" radiator, but a 26" is installed.
The radiator core support has been modified to make space for the 26", that tells me the car had no A/C and no special axle package.
The speedometer gear i found installed matches with the teeth count that should be in there with a standard 3.23 ratio axle.
Currently i have a 4.10 ratio rear axle with a limited slip diff (not sure what type) but i am convinced this is not original.
For the other things you can try and find which options were standard and which were optional, like power brakes, power steering, radio, etc. etc.
If you want to get a real simulation of how your fender tag looked like you got to do the home work and be honest to yourself.
A good fender tag example reflects the truth about the car, any fanatic will pick out the flaws and nail you for it if you would get it printed on a sheet of metal. (specially if you try selling it as original)
