All mk2 and mk3's have a 4.56
The 2.8 has a 4.35 unless it has factory fitted 31" tyres (not a UK option) where it will have a 4.56
The 2.6 on an auto box has a 4.77*
The 2.6 on a manual - don't know.
The MU 2.8 will more than likely have a 4.56
The LSD from the rear axle is interchangable. If you can find a pre 88 mk1 trooper with the 10 bolt rear axle, the rear LSD will fit in the front of a later 10 bolt front axle with a little tinkering.
*IIRC ;)
