170k miles on car. 2.2 liter.
I need to replace the driver's side "rubber" bellows (see generic bellows, HRK parts in attachment).
The passenger side bellows looks ok.
Regarding the passenger side bellows: leave well enough alone, or replace it also?
Thank you!

 

If you're replacing it for general wear & degradation, then the other side is probably in the same shape. But there's no real savings in replacing both sides together if you only figure the replacement itself.

But you'll have to remove the outer tie-rod end with it's ball joint. Unless you're careful about counting turns, etc, you'll probably get a suspension alignment after. Repeating that alignment is really the only motivation to do both sides together.