I’m not convinced it’s the diff as earlier you said you could drive as normal in Rear WD with handbrake on
This should mean diff ok if not it may be a 4wd issue and you’re in 4wd thinking you’re in 2wd
If selectors stuck as rob1miles suggested , An easy test for 4WD is just to jack one front wheel up , chock rear wheels, handbrake off, front wheel should spin, push down yellow knob for high4wd and wheel should not turn much, pull red lever back and watch yellow knob pop back up , push red lever forward and wheel should turn by hand , then pull red lever back for 4wdLo and wheel should lock again