let me help...
"Pacific truck performance rebuilt my LS and they lied. They told me the LS will work for everything. It does not. I have been fighting it, as I drive in the sand all the time. Therefore, I need a differential that will work for everything."
It sounds like you need to do a little more research on how our LS systems work. They are not "lockers" or anything near that. The factory LS is simply a spring-loaded clutch pack. In fact, they hardly limit the slip at all on wet pavement... sadly.
Is this a "off-road only" rig? If so, look into an aftermarket locker/spool/etc.