with an engine crane,it was easier for me to remove the gearbox out the passenger door.it is a bit tricky if there is an over drive fitted.You'll need to remove the seat box and floor panels.
I have dropped the gearbox backwards on another land rover I had but was so knacked after finishing the clutch job(didn't have an engine crane at the time just a mate to help).
As stated above you can't drop the gearbox as the cross member is weilded in unless you have a military chassis or has been modified.
Removing the seatbox will give you great access and allow you to inspect the chassis particualy those never seen before places at the same time (I re-coated mine with stonechip paint)