The postban RRA stocks that I've seen have roll pins pressed into blind holes through the plastic into the tube. If yours has the roll pins and you can remove them, it'll just be a matter of taking the mounting bolt out of the bottom of the adjustment rocker, sliding the old one off, sliding the new one on, and replacing the bolt through the rocker.
The roll pins are there as an extra measure. Since the RRA tube is full length and the stock can obviously not collapse and be usable, I'd personally be OK with that. If you can reinstall the roll pins you'll be even better.