Whitaker, got the center diff apart yesterday and needed to use my Blazer micro torch to get it hot enough to get the screws out. If you don`t have some kind of torch for heat you`ll strip the hex on the screws. If that happens use 1/8 drill bit and drill the head off the screws to get gears out of the diff and get new diff cases part #GS001. Got mine from Headrush Hobbies.com., nice place to deal with, come with new screws too.
My GST pulled hard to the right on takeoff and if I corrected the steering it would go hard left, almost crashed a couple of time because if it. Its not hard to get everything apart on your truck it just takes alot of time to do it right. I put 50,000 wt. in the center diff also.
The dust cover is just that, you will have to take the tranny out and take it apart to get to the diff. Check you manual on how to do this, check your gears then. I used Hob-E-Lube Moly Grease with molybdenum on all the gears, go easy on the grease, a little goes a long way. Hope this helps a little, Joe.