1994 Ford E-Series Van Rear Drive Axle Knocking

When making turns only, a loud knocking, thumping noise occurs at the back of the van. Looking for the obvious like a loose shock or exhaust system, there were no signs of a problem. Next, looked at rear axle bearing but while I was removing the axle, I had to take out the small differential gears. These gears were heavly galled, and very loose on the center shaft. Could these gears be locking up during turns and causing this loud knocking sound?

How do you inspect these gears and shaft?

Can they be replaced without replaciing the entire rear end?

Is it better to replace the entire rear end?

Thanks for your help.