For the Xcase the gear ratio is 2:1 for all models.

Further Clarification...
Many if not most early LS models (up to 1991) came with a Limited Slip which may be preferable on the road in snow.

As noted above the 94-96SR models have a locker. Their ring and pinion (R&P) ratio is 4.6x:1. In addition I recall hearing that some if not all of the 97 SR's may also have the locker.

Also the 98-2000 models with the Winter Package should have the locker (4.2x:1 R&P gears).

Bear in mind that for the models with lockers have the same sized differential gear housings so you can swap the gears. Additionally the later Montero Sports with the 3.5L engines (01-04?) have even higher 4.9x r&p gears that you can swap into the locker equipped Monteros.