Re: front diff question.
I don't think that cooking the diff in 2wd is really an issue. There is no (or rather negligible) power transfer to the front, and less stress on the VC than normal AWD operation. You'll see a higher load on the VC with the use of mismatched wheels/tires than you will running it with the front diff unhooked.
The rolling away on a hill without a working parking brake is a legitimate concern though. To the OP, this happens due to the fact that the VC will slip slightly allowing the rear wheels to turn despite the output shaft of the trans being locked in position. A moot point with a working parking brake, but something worth noting.
The only difference in an AWD and 4x4 diff is the axle disconnect. The t case, more specific, the viscous coupler is the reason you don't get the " axle hop/tire scrub" on dry pavement.
There are several issues you should consider like cooking your t case by running in 2wd, or parking on an incline in 2wd your truck will roll away even in park.
I don't think that cooking the diff in 2wd is really an issue. There is no (or rather negligible) power transfer to the front, and less stress on the VC than normal AWD operation. You'll see a higher load on the VC with the use of mismatched wheels/tires than you will running it with the front diff unhooked.
The rolling away on a hill without a working parking brake is a legitimate concern though. To the OP, this happens due to the fact that the VC will slip slightly allowing the rear wheels to turn despite the output shaft of the trans being locked in position. A moot point with a working parking brake, but something worth noting.