YES that'st true, actuator can be replaced, Mine was at Freightliner dealer in Portland, Maine, but Detroit Diesel wont do it, they say they need to replace the whole turbo and actuator.
Some Freightliner shops do it specially if the truck is under warranty.They don't want to change the whole turbo. It's considered a half-s job. It's a pain in the rear to calibrate the actuator with a existing turbo. Mine took 7 hours of labor (paid by warranty) to calibrate this thing...after I leave the, dealer, 200 miles down the road, guess what? Problems..Never heard somebody that had sucess changing actuator.
Detroit refuses to replace actuators because it can be a problem in the shaft that commands the VGT on the turbo and they can't fix it without replacing the entire turbo . I don't know. Mine didn't worked. I kept having problems on the turbo side.