It's considered a T3/T4 hybrid.
T3 meaning is uses a T3 bearing housing and guts, T3 family of compressor wheel and turbine wheel.
T4 meaning it uses a TO4E style compressor cover.
So, in reality, the only thing T4 about it, is the style of compressor cover.
FWIW, the TE-44 has been around since the early 90's.
PTE uses their own compressor cover, backing plate and turbine housing on their TE-44 turbos. The rest is standard Garrett/Turbonetics hardware like everyone else uses.
HTH
Patrick