Relatively simple job, but you need strong arms if you on your own. Remove front and rear props from transfer box, hand brake assembly and PTO cover support bearing and the gear assembly (makes reassembly much easier). Disconnect breather pipes and dif Hi/Lo rods. Undo the bolts that hold transfer box to main box and slide it back off the input shaft.
get some long (200mm ish) M10 bolts - cut the heads off and put a slot in the end (for a screwdriver) - undo the tranny box bolts and replace them one by one with the long bolts - when all are replaced slide the tranny box away from the GB, once the shaft has cleared lower the tranny onto yer skateboard
don't forget to have plenty for breakfast before you start