Pow. You know that sound--it comes from the Dana 30 under the front of your CJ. But was it the hub exploding, the steering U-joint failing, or the axleshaft snapping in two? If you have stock hubs, you've answered your own question. If not, odds are you just wasted a U-joint.
The Dana 30 uses 5-260X steering joints that are OK for most stock Jeeps and mild off-roading. But add stress like 33-inch tires, lockers, gears, and maybe some more horsepower and you've pulled the pin: it's only a matter of time before explosion.
Avoiding this scenario isn’t too difficult, but it can be costly. A very affordable option is Superior Axle & Gear upgrade axles for Dana 30s. These are made to the same quality specs as the original axleshafts, but accept 5-297X U-joints used in 1/2- and 3/4-ton truck Dana 44s. Drivetrain Direct offers these axleshafts for 1972-1986 CJs in kits that include the inner and outer axles assembled, with your choice of sealed or serviceable Spicer U-joints, inner spindle bearing and seal, and an axle snap ring. For about $200 per side, the upgrade may leave enough cash in your pocket for a lunchbox locker (which would be easy enough to add when you’re changing axles) or those aftermarket hubs you know you need.