Quick question(s)
 

1.Does the M104 engine 2.8 and 3.2 have an auxiliary water pump? If yes where is it?
2.300E 2.8 1993 Lower control arms (front). The ball joint is a separate part or is part of the arm.

Do you mean the ACC aux water pump? If so that's more part of the car than part of the engine.

I'm not familiar with the W124 but my guess is that it's part of or near the monovalve assembly on the firewall. Follow the heater hoses from the water pump along the right side of the engine.

Sixto
95 S420
87 300SDL

Aux water pump is locate at right side of engine.
lower control arm ball joint is part of the arm BTW if your vehicle is 4 Matic the ball joint is not part of the arm is separate part.