The Disco has a plate for easy access. I believe the 90 you have to "drop the tank" make sure you get that as close to empty as possible before you start. Have a gerry can full so you can get it refueled when you are done.
It takes about an hour to drop the tank. While you are in there plan to do some rust prevention while you are at it. clean the areas around the tank and protect them, also clean up the skid plate.
Most importantly remember that the 4 hoses that go into the tank are color coded. Write down the sequence!!!! Don't try and remove the hoses with pliers use your bare hands to squeeze the quick release clips out.
Have fun while you are doing it!!!