welcome to t he site. As far as I know, as 3B said, the trans location did not change. I don't have any newer trucks but, my understanding is that the change was the engine mount location. This has been my finding on most of the cars and trucks that I have worked on over the years. The auto manufacturers want to change tooling as few times as possible so, they will try to use as many of the same parts and assemblies across the different optioned vehicles as possible. AS you said, a change in trans location would change the hole in the floor, then also clutch linkage, driveshaft length, possible park brake linkage, and probably a number of other things I am forgetting about.
