Moes-performance sells the factory Mopar limited slip.
As far as aftermarket, I have only found Auburn and Yukon make one for the ZF rear end. I'm hoping they come out with an Eaton/Detroit truetrac before I install the mopar one I bought.
I believe the Yukon LSD is a rebuildable unit while the Mopar and Auburn are not(someone correct me if I'm wrong).
You can put a True Trac in the ZF diff,but it's not cheap. You need the older 9.25 gears and one long axle to do it.If you do a search on here,you'll find a few write-ups on what all is needed to do the swap to a True Trac limited slip.
It's definitely a better limited slip then the OEM clutch posi is,but whether it's worth the extra cost for the average guy is questionable,i definitely like mine,but my truck also gets used a little differently then the average truck,it see's it's share of water boxes and drag radials pretty well weekly in the summer,and the OEM posi does not like that combo,lol