We converted our 5ers Dometic A&E manual awning to Carefree electric. The Carefree Travel'r arms will work on either the A&E or Carefree 8' extension awning and tube. The exception is the A&E steel tubes, of which you would have to replace the tube - no issue with the aluminum tube. It went slick and we have been electric ever since.
The Travel'r arms are shorter than your manual arms, so you have to fill the holes at the bottom where your A&E cleats are bolted into the wall, but other than getting electric power to it, the mods were minimal.
The Travel'r arms rely on a track mounted to the side of your rig, and the awning rail for support. No special backing is needed. The Girard armless however is fully supported up by the rail and wall and must use some kind of backing in the wall. I don't think it would be something you could retroactively install on an existing coach without some work.
Travl'r power arms