I'd be VERY reluctant to get anywhere near that axle with a sandblaster. There's too much danger of getting abrasive material inside, where it's difficult if not impossible to get it all out. Give it a thorough cleanup with a pressure washer, put a pinion seal and hub seals in, and change the gaskets at the front and rear of the banjo housing. It's not uncommon for differential lube to get a silvery color, so unless the lube is gritty feeling when it's rubbed between your fingertips, don't fool with the bearings or the tooth contact pattern of the gears. Once the running fit of a set of used gears is disturbed, it's virtually impossible to avoid a whine.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!