I've never seen or heard of any 318 ever being offered with anything other than a 2 barrel. They wasn't a factory option. Probably dealer installed. I have family that retired from Chrysler
None of us know every avenue of this hobby. You should open your mind, all there is to know you have not obtained, and neither have I. "Any 318" you say, but yes, the 3.91 bore, 3.31 stroke 318 was offered with dual quads.