If you are looking for a Montero with a locker, you wont find it in the LS model, So SR is your only choice if your main concern is the factory locker. You could get a 92-93 SR with 12v 3.0 and locker but those are very hard to find. You could also get a 97 SR with the 3.5 SOHC and have the best of both worlds...And then theres the 98-00 gen 2.5 but then you have to deal with crappy axle gearing...For a core model a 97 SR would be the way to go..Factory locker, reliable 3.5 SOHC and 4.6 gears in the axles. My two cents..

99 Gen 2.5, fixing blown head gasket
89 SWB- 33's, ARB Front locker, SR rear locker/axle, SR F brakes, winch, WST Offroad Armor all Around, 2.85 Aussie T-case Gears (SOLD)
Sold: (2) 95 SR's, 86 SWB, 90LWB, 91 LWB
-Can Change a timing belt in my sleep..