00-01's have the pins in the head unit, but the wire harness lacks rear speaker wires. the only way to add rears is to tap the outputs on an aftermarket HU or get a new harness from Lucid or someone else that can allow you to use the stock HU's rear outputs.

 

Here's a site I did years ago about a Sony based stereo upgrade. Still going strong.

http://s2000.byteserve.com.au/audioupgrade

 

There is also the option, if you have the time and materials, to take the pins out of an atx power supply and they plud directly into the harness.

there was a post about this about a month ago. I'll post the link if i can find it.