67 GTX's had 2 style Air Cleaners, both were dual snorkel and niether was unsilenced. They were not transmission specific. One was spec'd for CAP (California emissions) and one was not. The only difference being that the CAP version had a small nipple protruding from the drivers side to allow a hose connection to the breather, the 49 state version did not have it. BTW, not all CAP versions were sold on California cars, some other states required CAP as well. If a 67 GTX has an unsilenced base plate (the smaller diameter unit that leaves a gap between the lid outer diameter and the base plate outer diameter) it was either swapped after the plant built it or it was a (very unlikely) production line mistake.