Yes, the rear electric locker was available from '96-'00. It was an option on every model of 4Runner, though, so it's not a sure thing on any model if it just "came" with the e-locker. The 2001 was the first year 4Runner where they attempted to add the brake-the-spinning-wheel computer control system that doesn't work nearly as well off-road as the rear locker.
The transfer case difference you are referring to is on different models within the same years. In '99 and '00 a Limited 4Runner had the "multi-mode" 4wd system, which basically added an open diff in the middle inside the transfer case so you could choose to drive it as a "full-time 4wd" with the center diff unlocked. But also in '99 and '00, the base and SR5 models (like my '00 SR5 4Runner "Highlander") had the 4wd transfer case that doesn't have the center differential capability - so it's essentially locked in either 4H or 4L, the same way that 4wd drive systems decades ago worked.
If someone ever chooses to get a 2nd transfer case (like a Marlin Crawler) for off-roading, you'll wish you had the simpler and shorter transfer case of the base or SR5 models, since I've heard that someone has already proven that the multi-mode transfer case of the Limiteds is too long for another transfer case to fit between the frame crossmembers and before the gas tank.
I'm not certain of the details of the transfer case used starting in '01.
Jeff
. In all years of Sequoia the center diff can be locked or open in 4Lo.
