The WRX STi donor will have an upper  flat-four and a 5/6-speed transmission. The highest spec donor would be an STi Type-RA or Type-R, which will have a six-speed transmission and a driver controlled central differential and limited-slip front and rear differentials.
The WRX STi donor will come equipped with a more powerful flat-four engine and a 5/6-speed transmission. The most advanced donor would be the STi Type-RA or Type-R, which includes a six-speed transmission and a driver-controlled differential system with limited-slip capabilities.