Transfer boxes

i have a 200 tdi discovery engine in my 90 and have a spare early discovery/range rover transfer box, i was wondering if there are any benefits to this transfer box such as motorway cruising. Im also running 265/75/R16 insa turbo special tracks if this makes a dramatic difference?
Cheers

The std Defender box is 1.4:1 and the Disco box is 1.2:1 As the 90 is lighter than a Disco or 110 it should be able to pull the longer gears ok. Low range remains the same.