If you feel it is necessary maintenance to perform than.
1) Lift Elan or plus2 with hoist or jack (level) (ramps at front, jack in the back works too)
2) Jackstands or safety lock on the lift in place and tested
3) Remove side fill/level plug. A 5/8 Square socket (8 point) or a 5/8 open end if it hasn't had the snot tightened out of it to stop that annoying gearoil drip.
4) If someone has buggered the shit out of the square head, stop. Time to go get a 10 inch Stillson
and have at it. Find a new plug too.
5) I have a funnel attached to a 5 foot length of hose and a wire on the funnel that I wrap around some convenient high point like the top of the window and insert the hose into the hole in the side of the gearcase.
6) A clean drain pan goes under gearbox side fill/level plug.
7) Pour in the gearoil of you choice into the funnel until it starts to come out of the side fill/level hole and stop. Before removing drain pan, pull the hose and let it drain, there will be some in the 5 foot section to drain out. Refit side fill/level plug.
Rewind the rest to get back to the beginning