I have read that the 5-speed speed sensor fits, is this 100% true? Say I used VTCs and a 2k2 ECU, could I still use the 5-speed speed sensor to get the speedo working, or would this cause a problem with the 2k2 ECU?

I believe the 2k2s use a sensor off the ECU or something.

 

I would use a 6-speed VSS that comes with Altima SE-R 6-speeds. I can sell you mine if you give me the VSS hole cover plate that came with your tranny.