Si has got at least 1 disco box going, dont suppose he'd want much more than the price of a chippy tea for it - i've seen them go for as little as 20 quid for the entire GB and TB assembly - also seen then go for a couple of 100 as well
it really is a bolt off/on job - driver seat and panel off, middle panel off, drivers floor plate off, both props off (do yer UJ's while yer at it), transmision tunnel off, tranny brake drum and shoe mounting plate off, speedo cable off, replace the tranny box mounting bolts with 180mm M10 bolts with their heads cut off - this is so you can slide the tranny box out untill the output shaft is clear - length of wood across the seats with a short strop down and around the tranny box (if you put some twists in the strop using the plank this helps lower is by undoing the twists) - replace the output shaft seal - smear some goo on the mating faces of the new tranny box and hoist it back up onto the 5 studs that you've cut the heads off - slide it back on etc etc
you'll also have to swop the depender tranny brake cable adjuster frame onto the new disco tranny box as they are slightly different - i've done a good few of these but this one (on my own 110) is the first disco box i'd seen that didnt have all 4 M8 mounting holes pre drilled - just had to drill and tap 2 of the 4, simple task to do
might want to drain and refill the tranny box with ATF etc
highly recomended modification