You can take the 4 screws off the corners and open the outer casing, dab some grease around the ring gear it will make 'em a bit quieter, but I wouldnt open the inner diff carrier case unless you want to put in new diff oil, if so you may need to buy a new seal kit or they might leak.
link Id just leave 'em alone unless you want thicker oil for your new brushless setup. If they break they are $16 on ebay. Im running 75k front 50k rear oil
edit :stock is 30k i believe