you use 92~95 OBD1 or 96~99 OBD2 ECU.. with harness, of course.

In order to make the 01' OBD2V2 GSR ECU to work in your car.. it's either you have the same keys(chips) out from the same car with the immobilizer unit(from ignition) then you would be able to drive it no problem..
if you happen don't have the exact same key(with chip) then just go down to the dealer and get the reset immobilizer procedure or ask them to get you a copy with the chip to match the ECU code..

Good luck