To elaborate on what Kurt said, your trim tag indicates your car was built the second week of May, 1968 (05B), however, your VIN indicates the car was built the third week of May, 1968 (05C), therefore one or the other has been swapped.
I would imagine it's the trim tag, but check the hidden VIN to make sure it matches the VIN on the dash, and post a picture of the trim tag.
Ed