Petty Enterprises Duster???

A friend of mine has found a 1972 Duster for sale that has a fender tag that reads only "Petty Enterprises". Thats it!! The car has a 68 340, but the seller says he has the original block. The dash VIN and door sticker match, and it decodes as a 1972 Duster. Anyone ever heard of this?

Appreciate any help here.