If you are talking about the oil tank, on our 1990 FLHTCU it is triangular in shape and on the right side behind the cover just in front of the right saddle bag and the drain plug is just above where the wiring wiring comes through , so every time you drain the tank there is a mess to clean up. I started using a vacuum pump and pull the oil from the tank. The vacuum pump does not get it all out but makes it pretty easy to change oil because you don't have to take anything off more than the fill plug and oil filter. The oil filter on mine is under the transmission in front of the rear tire - a lot easier to change than the newer filter in front of the engine.
Jireh sells an item: 97-304 $13.95 to use to help drain the oil, after the tank is empty and filled with fresh oil you use the turn on the item 97-304 and run the engine to push the remaining dirty oil out, after about 24 -32 oz of oil it will be clean oil. I saw a video and you can see the oil get cleaner as the fresh oil pushes out the old - then you refill the tank and all is well. I did not actually use it yet, but in sounds good.
I guess the newer engines make it a little easier to drain the oil but they also have the oil filter up front which make that part messy.