You would need everything from the head to the rear of the vehicle. To be legal, you would also need to insert 2 catalytic converters, one into each side.
I'm sure it'd sound great, and with the proper tuning (MAF sensor, intake, timing, etc...) you'd probably even boost your HP/torque.
However, the cost for doing it right would probably be prohibitive for a 1999 C1500. With headers, cats, mufflers, pipes, tuning, etc., I'd bet you'd be over $3k.