It is a pain in the ass. A wiring harness and a bracket are in the way. Tie a cord through the hole in the arm of the old check before you pull it out. Attach the cord to the new check. Pull it in. It's also helpful to be parked slightly downhill while you work.
Did you have trouble getting the new arm in? I read some tips about using a riibbon or a string to line it up when putting back together. Just curious.