Which wears fastest?

All tires are always under power when there's traction. When you're accelerating, the front tries to lift and transfers more load to the rear, so the rear axle has more load under power.

 

The front is not under power, take a front rearend apart. If the diff lock is not engaged the through shaft is not spinning the pinion at all. If you see a front rearend spin without the diff lock engaged it's simply from the speed of the through shaft getting it moving a little but it is not under power. There is a sliding clutch that locks the front differential in by engaging the through shaft or input shaft into the lower pinion on the front drive.

 

Yes, the front is under power, so is the rear, I have rebuilt several of both, I fully understand how they work. You need to learn a bit how differentials work. As long as there is traction, power is evenly distributed to all wheels. The only time any wheel end is not under power is when one loses traction, all power goes to the spinning wheel. It does not matter which one, front or rear, left or right, the spinning wheel take the power from the other three. Power will go to the least resistance, which is the wheel with no traction.

It's a very simple system that a lot of people don't really understand. You have 2 axles, each with a differential to transmit power to both sides even if they are traveling at different speeds (like when you turn). Then there is a power divider in the front axle that is nothing more than a differential between the rears. That center differential makes sure that both axles have power even if they are spinning at different speeds (like when the rear drives wear a little faster).

 

This is true!
When Interlock is not locked in you will have power to anyone of the 4 wheels , don't matter if front axle or rear.witch ever wheel has least amount of traction will spin.
Lock in the interlock and you will have 1 wheel on each axle driving.
If you got diff locks and interlock then all 4 wheels drive no matter what .