There is no lockright for the 12 bolt. There were a bunch of people interested in buying, and they were talking to Powertrax about making one, I'm not sure what ever came of it.

I'm running a spooled rear now, and so far I like it better than the lockright it replaced. The lockright was pretty inconsistent about when it was going to lock up. Sometimes going around turns, it would start locking, unlocking, repeat, and it would buck the whole truck around. Pretty annoying. The spool does wear tires a lot faster, so an ARB may be worth it, depending on how much you drive it and what tires you're running.