The shakers were available on 340, 383 4-barrel, 440, 440-6 and Hemi cars.
They were not available for a while do to saftey concerns, in a front end collision the hoods were going back through the windshieds and killing the drivers.
They were available again ( with crumple zones built in ) before the T/A hoods were introduced, so the whole "shakers were replaced with T/A hoods" thing is a myth.
T/A hoods were available on non-T/A Challengers as an option on 1970 and 1971 340, 383 - four barrel, 440, 440-6 and Hemi cars after the hoods came available for the T/As.
T/Ake care,
Barry