I have a pair of Kenwood KFC-S166 2-way 6.5" speakers that have been lying around for a year. Since they wouldn't fit in my Jeep that I recently sold, I just kept them and would like to install them in the front door of my 2000 GMC Sierra. Do I really need the adapter kit from Crutchfield, or is it simple to take out the factory speakers and install these? If it's a pain in the ass to install these without the adapters, I'd rather not do it until I get the adapters. But if it's pretty straightforward, I'll just hook them up as is. Any info is greatly appreciated.