I googled for this problem, but only found references to the 4 door Tahoe. Maybe some one here has experience. I have a leak on on the passenger side of my Tahoe. I lifted up the front carpet and the padding is wet. Behind and under the passenger seat is also wet. The rear passenger seatbelt wells are dry. I looked under the truck, but didn't see anything obvious. The only thing is the front door pillar, behind the kick panel has a little water in it. Possibly from a leak at the rubber wire protector that passes into the door.
Looks like I might have to wait for the next rain to see if this is the source of the leak. I hosed it down but still didn't see a thing.
TIA & Cheers