Just when I thought I knew what I was doing, now I'm not so sure. My 04 F-150 has keyless remote entry I wanted to add remote start to it, so I bought Ford's 2W7Z-19G364-BA (silver system). I was think I needed this unit because it has the four button remote. After I started preping the wiring I'm think maybe I needed only the remote starter unit. But how do you get the four button remote. Buy them seperately? Can I use what I have without it fighting the existing remote? Any help will be appreciated