Check this out!
Along with the then know '71 Swinger 340 Specials from 2 Western Canadian Dealerships (no mention of '72's, which hadn't been brought to light yet) according to this Mopar Muscle article about the 'scarcest' Mopars there were a few '71 or '72 340 Duster Twisters that were made - I'm on the possible tail of one here in Southern Alberta. Cliff