snapping noise in front end when in 4x4?

something went on my jeep today guessing its the axle or mayby a u joint thought i'd post on here to find out forsure. only happens in 4x4, its a steady snapping noise had it the whole way pulling another jeep up the road. then only had it when turning or or going up hills. and its on the drivers anyone know what it would be forsure?

Sounds like a front axle u-joint

I've been through this a few times. Definitely sounds like front axle shaft U joints.