there are a lot of things that can cause a clutch failure. the first thing i see in that pic is the flywheel pins. im not sure if they fell out on you or you got it like that, but the pins are supposed to be pressed in the flywheel and not come out. if they always have been like that, get a new flywheel and clutch shoes and go from there.

if they just fell out, id start checking the rest of the drivetrain. make sure you have no binding, the truck should roll smooth. next check the slipper clutch, make sure the pad is in good shape and its about 1/8 turn from fully tight. excess slipper clutch slipping can cause heat, transfering through the gears and into the clutch. also, make sure your not over geared. the stock gearing is 16/52. if you have larger diameter or heavier tires consider a 14 or 15 tooth clutch bell.