I just bought a new Silverado, actually a 07 Classic. It's a WT with no power accessories and a AM/FM radio. I want to install my Pioneer, but am told I need a $120 PAC adapter to do it correctly. The guy at Car Toys said I can install it with a regular wiring harness, but some things like will happen like the oil change light not being able to be reset and scanning may not work correctly. Is there something else I can do, or should I break down and buy the adapter?