Defender transfer box?

Hi folks.my pal has a c reg 110.he has done a lot of work to it getting it ready for mud and water.youtube landrover float test if ur bored.his is the first one.anyway its rapid of the mark bud not doesnt do much more than 60 and at that speed its revving hard.it was in the millatary and he has heard they were fitted with different transfer boxes for towing.so he wants to fit a disco or defender one.can anyone confirm this?and the best transfer box for road use and very frequent off road use as the ratios are different i think.cheers

same as civillian models ,but they come in 1.6 ,1.4 and 1.2 disco you will probably have 1.6 try 1.4

Thats what i thought.just wasnt 100%.many thanks