My drivers side seat sags to the left and the dealership has replaced every part of the seat, but it is still not comfortable. I want to put some thin padding under the seat cushion on the left side. Anyone take the seats out of their DD and take it apart? Thx

 

Look at it and find where the bolts are. Remove the bolts, remove the seat, find the other screws/bolts holding it together.

 

obvious

What I need to know is do I have to remove the whole seat with tracks from the truck or can I get under the seat cushion with the seat tracks still in place.

 

Generally easier to remove the 4 bolts holding the frame to the floor than removing all the bolts holding the frame to the seat from underneath while it's still bolted to the floor.