Yes defintily a seperate unit, its quite tricky to get to as well. Its got a filler hole and a drain - similar setup to gearboxes, you fill till fluid level reaches the filler hole
sweet wiil do had a look there but without taking wheel off, do you go in through wheel arch or from underneath?
What oil did you use? same as gearbox? or does the LSD req something special Toyota said multitrax but seemed a bit vague