*edit* Not enough info on the Cusco 200mm diffs

 

Ive read about people who have used both of those for drift and drag but I don't have experience pushing either of those so I can't say.
I would think if you asked the companies they would respond with a regular number like 500 just so they are safe if it does break, but cusco saying that is pretty interesting so maybe that is the one to go with.
Surely the next thing you will break is the R154, and keep an eye on the tailshaft for leaks.. you don't want to make a run with oil getting on your tires. it seems to happen randomly on r154s.

 

I went with the Os Giken They gave me a similar response. Several 1000+ hp cars with the OS giken rear diff and they break the ring gear never the LSD unit itself.