2000 Tacoma SR5 does it have a stock amp?

My 2000 Tacoma 4x4 extra cab does it have a stock amp in it? If it does where is it located at? Reason being I recently installed a new HU and speakers fronts are RF 5.25's 2 ways and rear speakers which are RF 6.5 two ways. Fronts sound excellent but the rears only bass coming out of them and no high end sound coming out of them. Anybody know if it has a stock amp because I believe this is the problem. I did use the stock wiring harness for the rear speakers. I may need to run speaker wire strictly for rears instead of using factory harness speaker wires. Any info is appreciated.
Thanks yall
Sittingbull2

 

is it jbl? and some of the tacomas and 4runners used almost like a mini amp that is either behind the radio, under or beside but you can just unplug it and plug in to the wire you unplug... but i have rarely seen the tacomas like that mainly the 4runners...

 

Well it was the stock HU I pulled out. It was the radio that had cd, and Tape deck, and radio all in one type. It says Toyota A56813 on the radio. If that matters any. Thanks anyway I believe I will just run speaker wire back there from my new HU. or maybe tear into everything to findout what there is.