well, being prepared is always the best thing on the trail. to survive a D35 break, here's what i'd recommend.
I would say you'd be safer with a limited slip rather than a full locker, like a detroit, electrac, or ARB. it's jumpy, so it'll lock the wheels in and out, which will definitely put more strain on the shafts, but you'll be loading and unloading rather than adding a solid force on it at all times... Which could be good or bad. Ultimately the choice is yours, but I'd suggest you consider an axle swap. for you, maybe the TJ D44 would be the best choice. check car-part.com for junkyards that have them around you.
Let me elaborate a bit more on this. There are three different types of lockers. Manual lockers and Auto lockers and the two main camps. In the Auto lockers there are subdivided into carrier and the lunch box lockers. Manual lockers are not jumpy. Basically you have a full spool (or Lincoln locker ) when they are turned on. They do not disenguage until the user turns them off. You get the best on and offroad experiance possable with these lockers.
Carrier auto lockers like the Detriot, or more specifically the Detroit No-Spin SoftLocker is rather smooth also. They have added some extra springs so the dog teeth enguage quietly unless under a load. The new Detroits do not ratchet like the older ones though. With these lockers you do give up some onroad driveability but you get a bulletproof locker.
Then there are the Lunchbox lockers. These replace the side and spider gears in the carrier. There are several weaknesses in this design. One, they use the stock carrier. Two, they only use one crossshaft to distribute the load. (Detroits and most Manual lockers use 2.) Because of the size inside the carrier the locker has to be compact. Lunchbox lockers will usually ratchet like the old Detroits did. They sometimes disenguage when you don't want them to also. When they reenguage they will eat themselves if you're under load(ie., stuck.) . Most people will tell you a lunchbox is ok for the front but wear out rather quick in the rear. Onroad they will let themselves be heard. They are inexpensive and can be swapped out for the original spiders in 30 minutes so you can easily remove them for daily driving.
Now onto LSD's. LSD's are catagorized from Tight to Loose. This is in relationship to the Bias. Tighter LSD's have a lower bias ratio while looser ones have a higher ratio. LSD's like the Auburn were notorious for twisting off the ends of axle shafts for a long time. They were popular in the 80's and early 90's. Other tight LSD's are the TrueTrac and the Powerlok. to give you a better idea about biasing, a TrueTrac will bias up to 2.5:1. That means the tire will turn no more then 2.5 times before the other tire turns once. The Auburn and TrueTrac uses gears so there is little wear happening.
On the other end of the spectrum is the Eaton Track-Lok. This is a simple design that is common on many OEM applications. These are the optional LSD's that Jeep has used. Basically, they look like regular open-differential carriers but to one side are some clutches and some springs. The clutches slow down the faster turning wheel and tries to bias the power as evenly as possible but becase of the design, it will be somewhere around 4-5:1. When the clutches get old they will loosen up until they act like open-differentials.
LSD's are smooth though. If you drive on a daily basis and don't want to compromise the ride and don't have enough for a manual locker then a LSD is your only option. They will require as much install as a full carrier will. They aren't cheap either. If you want locker performance, then get a locker, otherwise you will be dissappointed. If you still want a LSD, get one of the tighter ones. If you plan on having a LSD up front, be aware that the Jeep will exibit understeer. This isn't noticed with Lockers becase they disenguage when corning. LSD's will fight back though.
The most common reason for breaking an axle stems from getting stuck. The driver will try to spin the tires which sometimes causes it to bounce. This bouncing motion adds a lot of shock to the driveline and axle shaft. Larger tires will give the axle more leverage but that can work against it because of the shock load. Compound that with a locker. Many times the locker will unlock then it will lockup. (Open-diffs will send power to the tire with the least resistance so this saves you from damaging parts.) Then add the heavy throttle. Fast moving parts, bouncing then grabbing will break parts. Now that's not the only scenario but probably the most common.
Here's one of my friends. Happened while I was doing my D44 swap.
