An S60 is not a Dana 60. That's like comparing AFR heads to stockers and saying they are the same... I bought a 3.55 powerlok Dana for $100 on Craigslist, they are everywhere and they can be had cheaply. Dana 60 out of an old ford or dodge pickup trumps an 8.8 in terms of strength / reliability. I don't see a need for an S60 in anything short of a pro mod build, or just because someone wants to have one and say, look at that $2500 rearend... If the op has an 8.8 that will fit without doing a lot of work to it / axles sure it makes sense. If you are building one though, do it right the first time!