Defender/disco 2000tdi gearbox

Could someone help!!!! is there any diffrence between the 200tdi defender gearbox and the 200tdi disco gear box.
My understanding is that they are both just LT77, as my 200tdi defender gearbox has just given up what i need to find out is would a disco box bolt staight on or is there something i need to amend first.
My defender is a 1991 200tdi 110 and the disco is a 1993 200tdi (if that helps) Also does this apply with the transfer box.........

it's not just a simple bolt on swap, but the tranny box is - albeit a different ratio

disco gear box has a longer casing and mainshaft If you put it in a defender the gearlevers come up thru the seat box

Thanks guys that say me alot of spanner rash and sweat....