I have a 2005 z71 that will not spin the stock size tires in the mud even when put in 4 low the motor just bogs down like you are power braking on the pavement. The truck has 342 gears , brute force cold air intake, throttle body spacer and flow master exhaust. It will bog down in 4 high you can switch to 4 low and it does engage into low but makes no difference still won’t spin the tires