I though of the TDR mag fix for the sagging seat today so I got all the stuff to do it... $15. 00! Pulled the seat bottoms off (4 bolt's) installed the 2" foam and a piece of carpet with it for protection, Wow what a difference it made, I now sit real tall in the truck and the seat cushon is real firm, I knew I needed something before making a 4K trip! One other thing to add is when/if you do this is to swap seat cushons, mine was a little dogged out on the corner from getting in and out and this fixed all of that stuff. Yea a new seat foam would have worked too but heck it was cheap and painless.
Jim
Jim