Whoa! simopar7172, very interesting...
We know the factory could do some stamping mistakes, but we also know they built some pretty off-the-wall cars, so, what might this be? What more do you have on this '71 Duster? Where did you witness this fender tag? Someone you know, car show, random? Was it in Canada where the article from Mopar Muscle states they were built and sold? If you have any info, please pass it on - after buying and thus, finding out about the '71 and '72 Canadian Swinger 340 Specials, it would be interesting to know if these did/do infact exist as well. Thanks in advance... Cg