what do i need to do to run a cable speedo. i know i can use a bluebird one but do i need to mod the ecu or is that just for the auto ?????

I used a 120Y speedo cable for mine. These were still available new from Nissan a few years ago.
The only modification to my original ECU was to remove the speed cut.

yeah you also need a speedo drive out of another 71 series box e.g VL commodore or possibly bluebird and Stanza boxes. Bluebird speedo cable wont work it has a different connection at the cluster end from memory its a clip in job rather than a screw in one. As said above 120y as there longer or maybe early 200B we used a 1200 auto one for L series conversion and it had length to spare.

thanks heaps. i'm on it!!!!!!