1995 Chevy Tahoe brake light switch

I am also having a problem with my Chevy Tahoe's brake light switch. Originally, I was pulled over by the police and told my brake lights were out. I troubleshot it to the brake light switch. I replaced the switch and everything worked for a while. Eventually, it happened again. And again. And again. I keep having to slide the switch back into place because it gets very loose. I recently purchased this 1996 Tahoe from someone off Craigslist. He told me he had "just replaced the brake booster". So I know they were messing with the brakes. All that is securing the brake light switch in place is an "E" Clip of some type. As I research this more and more, I realize that this "E" Clip is not original to the truck and this guy shoved it in there as a quick fix. Bottom line, does anyone have a diagram or part number for this brake light switch retaining clip or a parts breakdown? Where can I order this too. Thank You.