1995 Lexus SC400 Stereo Wiring

Looking for a wiring diagram or a  breakdown for a 1995 SC400 ... a freinds car was robbed and by the looks of it ...it had a factory amp and I am trying to figure out if there is a way around it ...if you have of any of this information please respond ASAP

here is what i have...

1995 LEXUS SC400 2DR COUPE WITH 4.0L ENGINE AND STANDARD AUDIO SYSTEM

  Audio/Mobile Video          WIRE  COLOR  POLARITY  LOCATION   Battery  BLUE / YELLOW  (+)  RADIO HARNESS   Accesory  GRAY  (+)  RADIO HARNESS   Ground  BROWN  (-)  RADIO HARNESS   Illumination  GREEN  (+)  RADIO HARNESS   Power Antenna  PINK/GREEN  (+)  RADIO HARNESS   Amp Turn On  PINK/BLUE  (+)  RADIO HARNESS   LF Speaker (+)  BLUE   RF Speaker (+)  RED   LR Speaker (+)  WHITE   RR Speaker (+)  BROWN   Radio Security  YES

thanks another quick question....my friends amp from this particular was stolen....i want to see if there is any way possible to get the signal from the radio to go to an aftermarket radio...i can seem to find the wires that convert the signal into sound...