How many

Of the Duster "Twister" packages were made in 1971? I was just wondering. And what is a Twister? Ours is a 318 car with the 340 sharktooth grille, bench front, a904 auto. Were there any special features about this model besides the grill and stickers? y dad bought the car new, and we are curious if the "twister" is a rare package? If anyone knows anything at all about the twister, please by all means post it here...... Thanks

Triggerjay