Outer Limits 4x4 Board

GU gearing?
my mate is looking at buying s/hand 2000 gu st coil cab,the guy selling thinks it has 4.6 gears.it does around 2300 rmp in 5th @ 100k`s with 35`s.what do you think or is there a better way to tell???
ps stock turbo 4.2 d

that sounds about right tell him to take a stock GUTD if the revs are pretty close then they are 4.6

Last 2 numbers on compliance plate under Trans is fitted diff ratio. ie 39 = 3.9s

Bazzzlzzzzzzzle

4.6`s not the original gearing in this case,fitted after new