The Chevy dealer I visited got it working, but they had no clue either. They had to look it up on the GM online tech manual. Ironically, the Internet was down at the dealership for part of the day and it took a while, but they only charged one our $125 labor to change the VIN on the radio. They aid they weren't even sure if they were supposed to do it that way, but it worked. Remember to buy the GPS antenna. This one on Amazon works great.
http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1
It works on the dash or even better on the trunk lid. It is magnetic so I placed it on the trunk lid at the top edge with a little slack in the cord. Be aware that there are 3 or 4 different types of connectors on the plugs of various brands of GPS antennae. This one is for a Kenwood head unit.
I plan to install on Sunday May 10th 2015 so I will post pictures Monday. Good luck!
