1974 duster factory big block 400 car??????

Just saw this on ebay...thought the guy was blowing smoke but the vin plate looks legit....Must have been a error at the St Louis factory.... Actual "P" code duster in 1974....Interesting....thoughts???

[ame="http://www.ebay.com/itm/Plymouth-Duster-P-Code-1974-duster-big-block-factory-error-no-reverse-/331339002552?forcerrptr=true&hash=item4d2557f2b8&item=331339002552&pt=US_Cars_Trucks"]Plymouth Duster P Code | eBay[/ame]