As I re-call, if you loosen the two side 10mm head bolts, just under the muffler(each side), you should be able to push it back in.
I don't think the bolts actually go thru it but is crimped when those bolts are tighten down. I re-placed the left directional awhile ago
and had to lower the rear plate. That plastic also came loose. Once back together and that plastic pushed back in, nice and tight..