ah, I have strengthening ribs that were in the wayI got those two backing plates into the rear cross-member quite easily. It's an NAS truck but it's on a new (painted) galv frame - so it had all of the holes and relatively easy back-side access to get them in. The only challenge that I ran into is that the bottom hinge bolt is too long to fully tighten (or even close to fully-tighten). It runs into the NAS rear step. I could have inverted the bolt if I had thought about it prior to securing the lower bracket. Probably going to cut about 1/3" off of the end of that bolt to allow it to fit without contacting the step.