i figure gm hu's are pretty standard. picked up an 06 equinox and the stock hu fm was so-so. came and went. pulled it out and antenna wire was cut and spliced poorly. fixed that and i see bal/fade is set to driver speaker only. and turns out midrange was blown. but tweeter worked. centered bal/fade and all 4 work ok. maybe the fact that former owner had bal screwed up lead to overloading the driver speaker? i did feel side of hu where heat sink is and it was hot after 5 min of use. suppose none can say if that is normal as none feels side of unit in normal operation?