So why, if the PIC is driving the clock does the Shiftout command even need that parameter? Is the port associated with it (in your example PortB.2 or PortD.0) just a "holding place" for it or is the port connected inside the PIC itself? If I scoped one of those ports would I see a clock signal? (i'm going to try it...)

Also, how can a constant be used for ClockPin with a value of 0-15? How does THAT work?