Option 1: remove one side brakes and pull out the axle shaft. Then jack up the vehicle so the end with the axle shaft removed is now significantly lower. This will drain the majority of the fluid out although a bit will be caught in the lower diff hump. Reinstall axle shaft and brake on one side and re-fill.
this sounds like a terrible idea
Steven W
02 Dodge 2500
82 CJ-7 - sitting in a field...
"....Your theory is f*cked up like a football bat...."