Old thread, but a couple of clarifications should be made. The 44-45 case used in the Rebel is the same exact case as was used in older Dodge Ram 1500 trucks, say around vintage 2005. It is an electric shift on the fly system which has rear drive, 4-high, and 4-low. Once 4-high or 4-low are selected, the front and rear axles are mechanically locked together and must turn at the same speed.
The newer generation of RAM 1500 trucks use the 44-44 case, at least on the higher trim levels. The design and functionality is actually very similar. The difference is that the 44-44 uses a clutch at the front output shaft of the case. The clutch enables the "4-auto" mode. It also means that when you select 4-high or 4-low, there is no longer a mechanical connection between the front wheels and the engine's torque. Those modes simply cause the clutch to fully lock up and allow no slip. Of course, being a "clutch" it is possible slip could occur if you were operating in 4x4 in extreme conditions. Those conditions would almost certainly require you to be in 4-low for slip to ever occur. Installing oversize tires could also cause slip to occur.
That said, the clutch system offers a tremendous convenience for general 4x4 use in changing weather conditions. Pulling out of an unplowed snowy parking lot on to a plowed street might require engaging 4-high (4-lock) on the 44-45 (Rebel) case. As soon as the rear wheels came out of the snowy parking lot and all four wheels were on plowed pavement, binding would occur as you completed the turn. Meanwhile, a truck with the 44-44 case in 4-auto mode would pull out effortlessly.
I think the clutch based system has long proven to be reliable and convenient. GM and Ford use extremely similar designs. I'm not sure why this feature was removed from the Rebel. I guess if someone bought a brand-new Rebel and intended to pound it through deep mud every day or use it for rock crawling, the clutch-based system might wear out. But it is possible to have it both ways, apparently...the 2017 Ford Raptor has both a clutch-based 4-auto mode and mechanically-locked 4-hi and 4-low options. The Raptor case can even determine when the clutch-based AWD is being over-worked and automatically shift into 4-lock until the clutch cools down. That's a feature I'd like to see on the Rebel.
Clutch aside, the internals are no stronger on the 44-45 then they are on the 44-44 case. Anyone who has driven a good AWD vehicle in snow will certainly appreciate the total lack of binding while still supplying excellent traction in varying conditions. I'd actually like to see a 4-auto mode available on the HD trucks as well, but since none of the big three currently offer it, that's probably not going to happen for awhile.
