01 Denali XL Front Differential help?

Can anyone help me with the teardown of the front differential on my 01 Denali? It needs side bearings but the threaded rings used to adjust the bearings will not come out. The shop manual stated to screw them inward but they wont do anything but tighten up. I back the ring out and it turns out a feww turns and tightens up. I also have a broken locking tab that locks the adjusting ring in place once the load is adjusted on the bearings. I hope this lock ring is available thru GM. I also want to avoid splitting the case if need be. Any help is really apreciated. Thank you.