Pale Rider has a rear bumper for sale that he is trying to get rid of. It looks like its in really good condition...I don't know if he has had any bites yet and I bet he still has it. His is the integrated bumper/receiver newer bumper which should still work...I think he deleted his thread for the bumper sale, but couldn't hurt to ask
edit:
Also, i don't think there is any difference in the bumper/receiver on these trucks. The newer models have a receiver that is built into the bumper, which is much beefier...Not an expert on what is what, but my 2008.5 non tow package did not have an integrated receiver, it had a bolt on unit serperate from the bumper. My 2014 is also non tow package and has the receiver built into the bumper. No difference either way you go i don't think