Just to answer this question for other in the future, they do not fit. Despite the mount locations being the same, the actual mounts are lower on the 09+ rails, meaning the rails sit on top of the mounts and the injectors don't fully seat into the manifold. On the old rails, the mounts go over the top so the rails are physically lower. Still got a set of the 09 (same as 6.1) injectors with the rails which I intended to run anyways so there's that.