I agree that the popping sound is probably bad CVs. That wouldn't explain the fact that you are not getting drive to the front wheels though. How do you know that you are not getting power to the front?

Remember that the diff fluid can be a PITA to get it to flow out. Make sure you have a probe handy to keep clearing the drain if the fluid stops coming out. I only got about a cup out of mine when draining but then the rest all over the driveway when I dropped the axle.