I found the link below while researching the same topic.
I had our shop Nova Media Blasted and the bums must have blasted the door jamb so much they heated and distorted the aluminum Vin tag in the door jamb. (see pics below).
After carefully removing it and attempting to straighten it, I realized the numbers were now very faint. I found a place that restores tag (they DO NOT reproduce them or make copies). I will be sending out mine to be refinished and "restored".
http://www.classictiger.com/vinopin.html