Great start but why do you have to reinstall the factory HU? Metra and every other company out there makes interfaces for your truck that will allow you to retain onstar, chimes, turn signals, bose (if equipped-although I would bypass that crap), and everything else from the factory. You can even retain your steering wheel controls.

Over the years, we have switched to all Peripheral interfaces as they seem to have less problems than their Metra counterparts. They cost a few bucks more most of the time but they are much more reliable. Pac also makes a really good interface. Interfaces for GM's will run from $60 to about $125 depending on brand and what features your truck has. Like the other shops here, we have done hundreds of GM HU replacements with full perfect integration-no problems!