One of the dealership employees can probably get a lot more technical, but here's the year-to-year updates reported by ConsumerGuide, starting with the 1998 intro of the100 series:
LT
""Toyota's full-size sport-utility vehicle earned new styling for 1998, as did its Lexus cousin. That upscale Lexus wagon got a name change from LX 450 to LX 470, to mark the switch from V6 power to the SUV's first-ever V8 engine (with 4.7-liter displacement). Toyota stuck with the Land Cruiser designation for its new V8 sport utility. The V8 evolved from the engine installed in Toyota's Lexus-division luxury cars. The 4-door wagon came with permanent 4-wheel drive and a 4-speed automatic transmission. A 2-speed transfer case provided low-range gearing for off-road use, and a locking rear differential was optional. A Land Cruiser could tow up to 6500 pounds. Antilock brakes were standard. Land Cruisers were fitted for 5-passenger seating as standard, but a 3-place third-row bench seat was optional, boosting capacity to eight occupants. Rivals included the Chevrolet Tahoe, Ford Expedition, and GMC Yukon/Denali.
Year-to-Year Changes
1999 Toyota Land Cruiser: Rear air conditioning became optional this year, as the only notable change. Featuring automatic temperature control, that system was independent of the front-seat air conditioner. Rear air was available only when ordering the third-seat option.
2000 Toyota Land Cruiser: Land Cruisers gained standard equipment, including a new Active TRAC traction control system with integrated vehicle skid control. Using data from the 4-wheel antilock brake sensors and other sources, this system directed power to the wheels with best traction. Formerly optional, a power moonroof and leather upholstery became standard. Automatic rear air conditioning, independent of the regular system, now came with the optional third-row bench seat.
2001 Toyota Land Cruiser: An optional navigation system featuring an in-dash screen with map display via DVD was new for 2001.
2002 Toyota Land Cruiser: Toyota's luxury SUV got standard instead of optional 3rd-row seating, plus rear-seat automatic climate control for 2002.