The rear diff lock was available on 3rd gen Runners from 1996 until 2000. There is really no specific package that comes with a locker, its optional on most trim levels, including 4 cylinders and manual transmissions. Many Highlander and Limited models came with the rear locker, but you will find some SR5 and Base models with it as well. Don't write a truck off it it is not listed as an option, many people have no idea what it is and don't list it as they don't realize how desirable it is to many.