I have a 06 2500hd without onstar and was wondering if any one has a aftermaket radio. I was looking at the Kenwood ddx318 but they say I need to buy a extra $100 part to make the door chime work. I could careless about the chime but it may affect other electric parts in the truck. I really want the nav. in the truck but I dont want to spent 4 truck payment to get it. Any ideas??? http://www.crutchfield.com/p_700318G610/Kenwood-DDX318-Navigation-Package.html?tp=20212