Nice work. I'm surprised they didn't change out all 4 backing plates.
I have the 4 originals I pulled from mine last year when I went with the Dexter self adjusting brakes. They were/are in great shape. I thought for sure they would have been grease soaked but the seals were in good shape. I replaced them anyway.
My tow vehicle is way overkill for the for the 9800 GVW Jayco but it is nice to maintain a set speed up steep hills and 12+ mpg doesn't hurt
Edit: I just noticed my sig pic is of my old dually. That was the day I picked up the camper in 2007.