auto transmission oil ccoler pipes 300tdi

had to change the auto transmission cooler pipes on my 300tdi disco .first problem was freeing the nuts from cooler any way with a lot of heat and some brutal persuasion managed to get them off ,now my next problem , how do you get at the oil cooler nut thats on top of the gearbox ? anyone have any experience with this or have and tricks to get it off as its a 24mm nut the spanner quite large and cant seem to get the angle
on it any help would be most appreciated theres no mention of the cooler pipes in the manual so thats no help

if you get stuck place jack under t/box undo mounts and lower box enough to get in