If it has a Precision 3-bolt turbine housing, there will be a part number cnc cut into the downpipe flange side of the housing. If this number says THB3-76 or THB5-76, then it is a P-trim turbine wheel. The 76 in the part number means P-trim. If the part number on the turbine housing says THB3-80 or THB5-80 it is a GT-Q trim. The 80 designates GT-Q wheel. (FWIW, Precision discontinued the old "Q-trim" wheel 6 years ago. All of the "Q trim" wheels that people like to call them have been GT-Q trim wheels since 2000 if the turbo originated from either PTE or Limit) If you don't see a part number on the downpipe flange side of the turbine housing, then look on the compressor cover discharge, where the hose slips onto the discharge, most companies engrave the model of the turbo there. Most TE45 turbos that I've ever seen come standard with the P-trim wheel. The GT-Q wheel was optional. Another difference is, the GT-Q wheels torque nut sticks out past the edge of the turbine housing discharge where as the P-trim wheels torque nut is either flush or recessed slightly.
HTH
Patrick