I found nothing in a search on this, so if anyone can provide tips on removal and replacement of the power brake booster on a 91 deville w/ abs, I'd be very grateful.

I have a parts car wit a good booster on it and the brake codes call for the same replacement part so I intended to use the booster from the parts car as a replacement. I'd like to know whether the four bolts barely visible under the dash on the firewall are the only bolts holding the booster on.