Hello Brett,
Of course, the Theravada tradition is the only one that supposedly follows the Pali Tipitaka.
– However, CURRENT Theravada teachings have been heavily influenced by Buddhaghosa’s writings, especially his Visuaddhimagga.
– Instead of following the Tipitaka, most current Theravadins follow the Visuddhimagga.
That is discussed in several posts at, “Historical Background“