MY 06 GMC ENVOY DENALI WHEEL HOPS AROUND CORNERS
WHEN I TURN CORNERS THE REAR WHEELS SEEM TO HOP LIKE THE POSI IS
STUCK IN LOCKED POSITION IT HAS THE G80 REAREND COULOD IT BE A BAD
4X4 SWITCH OR IS THE REAREND SHOT
I would find out if it has a limited slip rear end. If it does (pretty sure it does) then I would change the rear end lubricant making certain to use what GMC recommends. This usually involves a friction modifier as an additive or part of the lubricant.