The dust cover has four 1/4-20 screws holding it on. 2 in front, 2 in back. I'm not quite sure why you want to take it off, but it won't do any harm if you do.
It sounds like you are trying to take the bellhousing off, while the engine is in the truck. This would be a mistake, as it is not practical to do. The bellhousing is held to the engine block by 6 bolts with a 7/16-14 thread. There are 2 bolts on the top which are accessible, and 4 bolts inside which can only be accessed by removing the clutch assembly and flywheel.
