You are talking about the data tag on the core support? Like this:
View attachment 124885
As I understand it, during assembly before it reached the end of the line and had things like a VIN number or even doors they had to have something on the vehicle to give it some basic definition to how to assemble the thing (what exterior color, interior color, cab length, box length - etc things that happen long before a door gets attached or a VIN riveted on.
About the only 2 things I know is that my VIN ends with 35002 - and you see the next to last line does as well - production number.
and I have a 7' bed - I assume that is what BOX7 means.
There are guys in the mustang world that can decode everything about the 'stang but doubt they would help much with rangers.
Don't know that anyone here worked in an assembly plant or knows them so detailed as to be able to decode..
FWIW, 83 was the first model year of rangers, so even though some parts were made in 82 they all went into a "1983" model.