Yes, the bottom skid plate must be removed. To get the new oil in. I used a one gallon milk jug. Rinse out the jug and dry. Put a small hole 1/16” in the plastic jug cap for a vent and another hole in the cap for a tube long enough to go from the outside of the Jeep to the gearbox. To make sure that the oil was flowing, I used a clear ¼ ‘ plastic tube. Pour 1 quart of gear oil into the jug. Put the cap on the jug to avoid spilling. Insert the tube through the cap into the milk jug. Raise the jug up, outside the Jeep, (on the roof) above the gearbox enough so that when you siphon the oil out of the jug it will flow. It will fill slowly, but it will be worth the extra time and you won’t spill a lot of oil on the ground. After a few minutes, watch for the gearbox to fill. Once you see it start to drip out of the fill hole, pull out the plastic tube and reinstall the fill plug, and you are done. When filling the gearbox, be sure to use a drain pan under the gearbox to catch the drippings.
It is much easier when changing the rear gearbox oil to support the Jeep by the body’s jacking points instead of supporting the Jeep by the rear axel. So if you allow the rear axel to drop down under it’s own weight while the Jeep is in the air, you can get at the rear fill plug so much easier.
There are flat washers on both fill and drain plugs, front and rear. Be sure that the washers get reinstalled.
All the best and good luck
2007 Jeep Patriot