Hello All, I recently bought a 2019 Tahoe LT. I notice there was a noise on cold start from right side for only about 10-15 secs until the truck warmed up. I noticed a missing manifold bolt on the back right side that looks like the culprit/Exhaust leak (pic3). fingers crossed.... So then I started looking over the engine and I found a spot on left side that 6 bolts are missing (pic1). Can someone tell me what those are for. I'm guessing some sort of optional part? Also I seen one missing on the right side by the alternator. (pic2) . I'm just curious and still learning! I appreciate the feedback!