is it possible/straight forwardish to fit an auto box into my 1993 200tdi 90? my box needs changing and looking at opitions

i have a 1993 d90 200tdi and have fitted a transfer box from a 300tdi disco, all works fine but i find the gear now tall, does anyone know if the gear from the pto point from my d90 transfer box will fit into the disco one and if that'll lower the ratio back down?

hello, i have a 1993 200tdi 90, when i put my foot down it pulls to the left, not to badly but enough to have to steer right a bit to go straight, under breaking its dead straight with no pull either way, all the bushes have been changed so any ideas would be great, thank you