2003 GMC Sierra Radio Wiring Harness

I need some help finding a wiring harness for my 2003 GMC Sierra. I would like to install an aftermarket head unit but I've been told by Metra Electronics/Axxess and Scosche that I have some special wiring harness that so far everyone is baffled by. Please see this link for photos: http://www.maddoxspace.com/images/wiringharness/     * No OnStar is present in the vehicle.     * No Standard or Premium Bose system is present.     * I've tried both the Metra Electronics GMRC-01 and GMRC-02 wiring harnesses, neither of which fit my truck.     * Metra tech support tells me that I have a Chevy Malibu harness coming out of the vehicle.     * Scosche tech support tells me that I have a rare Class II, 11 bit harness coming out of the vehicle. Will someone please advise me if there is any wiring harness that will fit my vehicle? Thank you! The above photo depicts the problem. The grooves in the GMRC-02 do not line up with my wiring harness. Close by no cigar. The GMRC-01 is the same way.2003 GMC Sierra | Ext Cab | 5.3L V8 | No OnStar | No Bose

Assuming no CAN or similar data is involved plan be would be to work out, either with a DMM or by accessing a Chilton or similar manual what each colour is and then soldering to the new head unit's plug.

Is there an acronym guide somewhere so I can understand what you just wrote? CAN? DMM? Must I really resort to soldering to the new head unit's plug? Here I thought I drove the most common pickup truck on the road, a GMC Sierra. This is just astounding that the wiring harness is such a one-of-a-kind. Is it possible that the wiring harness was somehow changed out at the dealership by the previous owner or something? I'm at a loss.2003 GMC Sierra | Ext Cab | 5.3L V8 | No OnStar | No Bose

No please don't attempt anything like soldering. If you don't understand CAN read some posts on CAN and Data on the Gen and Misc. Topics section DMM means Digital Multimimeter. I'll say no more.