kwoodwo

Update: spent $1200 getting new front differential bearings installed. Problem is still there.

It is not the flex plate. You are describing something entirely different. When the truck is in neutral or park, there is not tapping. You can rev the engine in park or neutral and there is no tapping. However, once it is in gear there is tapping at low rpms around 20mph-30mph when you lightly "feather" the gas pedal. The GMC dealer told me that it has something to do with my front differential but I am hesitant to let those guys have their way with my truck without knowing for sure what it is.

Anyone have a fix for this? Same thing happening to me as in the video on a 6.2 denali.