If you jack up the rear end of the car as far as you can; leaving the the front end of the car on the ground, all the gear oil will transfer to the front of the transmission. I did this yesterday, and I got about one or two spoons full of oil that drained from the speedo sensor opening, not even enough to have to top off.
NOTE: I had just changed the gear oil on the transmission about 6 months ago, and knew it was full. Plus I checked the oil for good measure the next day when I had it up on a drive on rack.
