2003 Silverado reg. can sportside shortbox. 5.3 engine. 17 inch steel gm wheels, Yokohama g015 E range tires. Suburban duel piston calipers(back) 2008 Silverado brake upgrade(front). Had this setup for a while with no issues.Went mild logging road driving about1000km back, and truck developed a "shutter" at about 40 and worse at 20 km ONLY when slowing down. Replaced ALL brakes,front wheel bearings, ALL front end components (was time) except lower a-arms/ball joints. Hade wheel alignment. Still vibration as slowing , first at 40 and slightly worse at 20 to zero. The vibration seems to start at the front and run thru to the back. I joints seem fine.While stopped at light,and kicked once(slightly) ,hence the new wheel bearings. Still have the annoying vibration. Looking at the VVS on the transfer case now. Any ideas guys?