i haven't run into too many trucks outfitted with 3.92's that weren't LSD... just for whatever that's worth.. I'm not saying they aren't around, but I think maybe they are uncommon..
and the thing about LSD- those dang c-clips.. they sure like to displace themselves.. when that happens, you get tires that bite the inside edge when turning.. which, makes you go sideways if you stiff foot it, just like a locker- no?
i had 3.92's on factory LSD, and bumped to 4.56 on a rebuilt factory LSD.. my rig had 145k on the clock or so before I did it, and the c-clips were a-okay.. I don't abuse the rig in any way though, and never EVER pull bone headed stunts like 'burn-outs' on dry pavement, spins on loose surface transitioning to dry pavement, or any other weird stuff that wreaks havoc on rear diffs, or drive trains in general... I like my feeble transmission too much to stress it when I don't have to..
anyway- the reason I interjected that is this: those c-clips fail, and you have clutches that grab.. and basically have enough power being applied to one side of the axle to get yourself into trouble, but not enough to get yourself out.. it kinda sucks- because an LSD that has broken c-clips bites, but doesn't bite very hard- it loses grip under heavy pressure and behaves like an open diff..
the answer to this is one of those Auburn units.. or another that doesn't have a really weak design.. I say this being kinda funny, because I DON'T have dislodged or mangled c-clips that I know about... when the snow falls, which is rare here, but if it does- that's a really bad time to find out your driving a pseudo locker that doesn't really lock, but bites enough to spin you.. if I lived in a snow prone area, i'd rather be driving a open than a factory LSD, but i'd rather have an auburn over either.. they are predictable..