My car has a clean underside so the $10 triple square bit set from the parts store did the job. A rusty underside might require a better quality bit. You also need a suitable socket for the nut at the wheel end of the shaft. Hopefully you can jam something through the open CV joint basket to hold the stub while loosening the nut, if the brakes and/or wheel chocks aren't enough. I don't know if the warning applies to MBs but in FWD cars in which the axle goes though the hub, you're not supposed to set the weight of the car on the hub if there isn't an axle in place. You might consider moving the broken off stub to the parts car so you can roll it.

Sixto
87 300D