Outer Limits 4x4 Board

Hey all, I pulled my rear diff apart (axles and now center). On the DS, were the short axle connects to the center it has broken the spline it used to join to. Is this a new diff or just a small part that can easiely be replaced. If i went out and bought an auto locker would this fix my problem. I know this isn't common so anyhelp would be great. The splines on the end of the axle are slightly twisted should i replace them asap?

Cheers Josh