Weeks back while running a line for my rear camera install, I noticed water puddled on both sides of my front door sills. No sunroof, windshield was replaced back in May but didn’t think that was the issue as there was no evidence of water in kick panel areas, etc. I used the hose over the cab and saw water coming in from the bottom of the door gasket. I ordered a replacement for both sides, replaced, and after using the hose, drive thru car wash, and about 3” of rain yesterday, no leaks! Although the gaskets didn’t show signs of wear, damage, I guess age played its role. Maybe this will help some who have experienced find resolution.
2011 Chevrolet Silverado 1500 Extended Cab Driver Side Body Mounted Door Weatherstrip Seal