well i got one of the diff carriers today. i put the gears in, the spider gears and when i go to put the robinson racing ring gear on, it dont fit flush on the diff carrier and the spider gears inside dont turn good. but when i use the traxxas ring gear it fits perfect and all the spider gears turn great. i might have to just use the stock traxxas ring gear. i mean its metal so im not afraid of it stripping out. i just want to use the robinson racing gears i have for the diffs. i still have the robinson racing pinion gears i can use. i dont know if i should just use the stock black plastic diff housings, or get new aluminum ones? i really want to stick with the blue aluminum diff housings! i just hope the 4 screws that hold the ring gear on dont break again!