gearbox/ transmission

hi, i have a 1995 N-reg disco 300tdi which i use for towing. it has done just over 117k. im starting to feel alot of slack in the transmission when changing gear or pulling away which i believe is due to the transfer box. there are no strange noises apart from clunking if rough letting clutch up and the propshaft/ joints are good. but with the vehicle parked with handbrake on and in gear i can twist the front propshaft about 1/8 turn.

i also have a rotten J-reg 200tdi disco which has good transmission and running gear with no slack when driven. will the gearbox/transfer box fit my 300 tdi engine? i know reverse gear is in a different position, or can i separate the gearboxs and transfer boxes and use the 300 box with the 200 transfer box?

I understand that the transfer box is common to both 200 & 300 tdi