That's not a vintage neck, it's got a biflex system.... THEREFORE, replacement decal is the only thing I'm able to figure out, as Fender, even in their horrible fire-sale in the early 80s, would never allow a guitar out of the factory without a serial number.

Also, if you look closely at the decal, you can see that it's actually lighter than the headstock, and the cutout looks a bit "off". My guess is that it had some work done, and the decal started to peel, it was replaced with the only available decals in stock back in 84, the vintage reissue decals. Cool guitar nonetheless.