Every GM 4x4 I've owned since the '80 K10 shorty, came with what GM calls a locking rear and all worked fairly well, provided they had decent tires on them.
While I haven't done much "adventuring" with them, neither did any of them ever get stuck in snow or mud. The '80 came to me used, with "car tires" on it. Replaced them with Firestones that resembled BFG T/As back in the 80s, world of difference. Made it through some impressive amounts of snow with that truck. Hunting buddy had an '81 Chevy, also with the rear locker, which also got around pretty well.
He finally traded that with over 200K miles, on a new Chevy 4x4. The dealer he bought it from, didn't order their trucks with the rear locker option at the time, like most other Chevy dealers around here did. Said he didn't think having a rear locker was a big deal?
First deer season, he backed up into a snow covered field to retrieve his buck and got stuck. One rear wheel dropped off the end of the sluice pipe at the field entrance. Twisted the truck enough, that one front wheel had no weight on it, so she just sat there and spun in FWD. Needed a bit of a pull to get it out onto the dirt road. Told him he might as well be driving a Nash, without at least a rear locker? He didn't keep that one long, replaced it with another new truck w/locker.
Lockers all around are the cat's ass if you're gonna regularly be going off road. Otherwise, just the rear locker is usually enough? Has been for me, so far for normal road use. Have an old beat to hell Bronco II at hunting camp for off road use. Regular little mountain goat in the woods. Locking hubs, five speed and it stays in FWD low at all times. Haven't had that stuck yet, either.
