Japanese auto makers don't like to have multiple wire harness for different model vehicles.

But they do have different Instrument Clusters/Unified Meters for different trim models.

I believe the Premium sound also comes with the upgraded cluster, so it'd probably have that stuff for the radio, and the upgraded cluster probably comes with the different harness.

On the older vehicles, the Bose sound system had it's own harness that was unique to the Bose equipped vehicles due to the internal amps in each speaker. So I could see the difference happening quite easily.

Oh, yeah, that's right. I fogot that there is a trip computer in some of the trucks... so that makes sense. Do the trucks with the RF stereo also have the trip computers, as far as the OR, or is the trip computer only on the SE's?

I'd bet that the instrument clusters are the same. The software that they are loaded with ahs different features enabled. From a financial perspective, you don't reinvent the wheel. As for the connectors on the amplifier, I might have a wee bit of knowledge of Bose amplifier.

So, based on your logic, if I get a steering wheel with audio controls and install on my X that didn't have it, it should work?

I would suspect that a sub harness in something like a steering column would be different. The main harness will most likely be the same. My logic refers to the instrument cluster itself. Each cluster will cost many hundreds of thousands (maybe even millions) of dollar to develop. Then more $$$ to qualify and validate (especially because it's a safety critical system). I design amplifiers and we write the same checks. It's much more cost effective and efficient to commonize hardware and just change software.

The instrment clusters are not the same. It's been discussed in another thread.

And no, if you put an audio control steering wheel on your X, it won't make the radio work. The radio has a seperate input for the steering wheel controls to work. If your radio didn't have it, it won't work. You'd have to switch the radio, the Air Bag clock spring (which has the extra wiring in the it) behind the steering wheel as well as the steering wheel.

Installed the Alpine speed pulse generator. Cost an extra $200 but it's done and the Kenwood Navi works great .