help with Rear end

[pgh r]

Hello everyone I have a question that hopefully someone can answer. On the way to work the rear end locked up on me. I have a 99 4runner with abs, 16" tires, 410 gears, and no diff lock. My mechanic told me it's easier and cheaper to buy the whole rear end and not rebuild one. So I've been having a hard time finding one off a 4runner. Is there another model that has the same rear end like a tundra or something? Thanks for any help