Factory 3 speed Demon 340

Code D13. The three speed was the standard transmission on 1971 Duster/Demon. The 4 speed, and 727 Auto on column and floor shifted were extra cost. That being said, the three speed even though it was standard is more rare on 340 cars. The exact number I do not know. I know of a 1971 Duster 340 3 speed car in my town.