New to this forum. just got a 86 t/a couple of weeks ago. There is a tag on the left side of the core support with numbers. when i pull the bumper off there was the same # on the crash bar. Its not a vin related #. Any clues??

 

That was the id number to identify the body and match it to the VIN before the body had a VIN on it ... all the document (buildsheets etc) had both those numbers on them and if you still have the barcode sticker in the passenger door side you see it on that one as well.

Just a sequence as the orders where processed and the build started to keep track of things.