Find an old tech's handbook online (SX2000 light or 3300, I release 3.2 has info)... it is essentially a single 16-port DNI card, the 16 jacks are ports 1-16.
In the SX2000 it is just like any other per bay, except it only has one card. As far as which PLID, well, your kind of on your own there, connect a phone and see what extension you get maybe, then do a locate?