Bought a 1994 Bose Gold head unit (part # 16166166) to go in my 92 STS. The one in the 92 looks the same but doesn't have a balance knob, and the '94 head unit sounds MUCH better.

Unfortunately, the 94 head unit isn't compatible with the '92's trunk-mounted tuner, so there's no radio reception. Its worth it though for the massive sound quality improvement. The '92 with the same amps sounded narrow, muffled, and dull. The '94 HU is bright, powerful, and clear.