Hey guys have 2005 E55 with 107k miles.
rebuilt the front suspension, now going to tackle rear. What should I be changing on rear suspension? I have new rear shocks and bags that's it rest is still original.

 

For what it's worth, my car has 156k miles and still has all the original rear suspension aside from the air springs and shocks. It was a SoCal car all its life. No rust and well taken care of. In the front, It has new struts and thrust arms. Otherwise original.

 

I have a 07 E63, and when I did my suspension, I replaced everything. As the bushing in your control arms, thrust arms, tie rod, lower spring arm wear out.
Although, your suspension might look good on inspection, trust me things have worn out. If you goal is to keep this car for a very long time, then it's worth.
If not, then let the next owner spend his coin on it. My car rides like brand new, but it did cost me some serious coin.

 

Thanks for the response.