broken left front hub....very worst a broken left front axle?? If it's pulling right when only in 4wd then the r-front is doing all the pulling and the left none..?? Would a broken spider gear cause this?
Perhaps. Since the "hub" is basically a drive flange, you would be hard pressed to break it. I have to assume if you break it, the wheel would fall off? The stub is splined to the wheel stud flange. If that breaks, your wheel goes rolling away (caliper probably hold it on for a short while), but there is so much steel there, other parts would give first.
I understand mine is slightly different with it's inboard rotors, but you understand the concept:


If the axle breaks, I suspect you would simply have a "cad-like" operation assuming you have an open differential. I would guess it would act like CAD with a hose missing where neither wheel really pulls.
Same if a spider gear destroyed, except I assume you would have hellacious noise, and an explosion quickly? The ring and pinion and driveshaft is always turning even in 2wd.