CLSegraves1

I don't think I've ever read anyone saying the pins/springs fail (other than due to a botched install).

00t444e

I have seen u-joints and axle shafts break and the lunchbox locker be fine.

5-Speed

Speaking of the pins/springs, that is the reason why I went with a Spartan over the others. They seem to have the best/strongest design. Well that and they come with the hardened cross pin.

2drx4

Those two groups are not mutually exclusive.

IMHO any failure is unacceptable. I would rather install a locker that I can almost guarantee won't fail, rather than install one that solidly might fail and 'hope' that it doesn't destroy other parts in the process. Also, by going to full case locker you pick up some strength in the gear set (often a significant amount) by limiting ring gear deflection, as the ring gear flange on most stock carriers is woefully inadequate and will deflect considerably under minimal load, while the windowed center of the carrier will also contribute significantly when the load is applied in line with the windows. Most good full case lockers will probably outlive the gears, which is the standard I shoot for with the rest of the axle components. Once you're seeing ring and pinion failures it's time to upgrade to a larger axle in general, or spend real money on stuffing larger gear sets or bearings in, cryo treatment, or adding load/deflection control devices (not all of these options are feasible or at all intelligent on all axles).

I have seen stock carriers break in half. Rare, sure, but it happens. They'll also egg the holes for the center pin until bad things happen.

However, as I said earlier, it is a bang for the buck option to use a lunchbox locker. I have them, I'm not above it, it's just not the best solution.

00t444e

A good heavy duty diff cover helps prevent deflection.

2drx4

Minimal compared with a better carrier. And I mean minimal.

To really make a difference you run studs instead of bearing cap bolts with a cover that then picks up on the studs. But it all needs to be a very precise fit in order to be worthwhile, typically requiring shimming on install. If you look at some of the better aftermarket center sections, they use much beefier caps with larger bolts or studs as again this is a problem area.