I bought a 94' 5.7L Firebird a while back, and noticed the previous owner had replaced the head unit. I had a head unit from my previous camaro (the stock bose one- it looks like a U1T in the book, but I don't know what the original unit was) and noticed the bose seemed to sound much nicer than the current system. I switched the head units, so now it seems to be fully stock, but the audio quality is still low. My brother noticed the rear speakers in the back seat were disabled- after reinstalling the stock stereo, I noticed they did not come on then either. I checked the amp, and it appears to be unaltered/present/in working order. Is there any reason they would have disabled the back speakers, and is there a way to reenable them? Also, the steering wheel radio controls do not work. Any diagnosis there?

Happy Thanksgiving.