It depends on how you want to do it. I swapped my 203 for a 205, and used the 203's intermediate housing - which is shorter than a 205's intermediate housing. Because of this, I had to have my rear driveline lengthened and my front shortened. Also, because of the front's CV joint, I had to trim a rear corner on my C6's pan
While it wasn't my cheapest option, my time limitations dictated I go this route. This wasn't hard, either