New Crank Position Sensor

I'm the guy running a 2001 S2000 engine in an MGA. The car only gets Club use, but back in Easter 2014 it started pinging/pinking under load, especially up hills. It was suggested it could be the CKP sensor, so ordered one from the USA. It arrived a week or so ago, but I notice it is a complete unit...the original CKP screws into the block, and the electrical plug just clicks into it...on the replacement, it is one unit from wiring loom connection to the sensor itself....is this usual with after market replacements?