Hello, I have a mid 2009 Macbook pro 13. I have bought a hard disk cable that looks almost the same as the original one except for greater width and shorter length. I guess that this new cable fits the 2012 model, SO YOU MAY HAVE TO UPDATE THE GUIDE accordingly.
Electrically the wider cable also works on the mid 2009 model (at least for disk access) though it does not fit mechanically.
My friends be careful when you buy this part.