Did you ever figure out a sollution? Im having the same exact problem

Hey Bos, what did it take to fix this problem. I have a 97 3500 my amp gauge is sittin on 8 when its running, but my odo, speedo, and tach quit working, my lights to indicate its ok to start quit, and usually my engine light is on and now its not. If you or anyone else can give me an idea. I appreciate it very much. Thanks