Hi,
I lurk on SAU mostly, but I own a HR31 coupe and have done manual conversions on aussie R31s before.
Tailshaft - If possible, the easiest thing would be to get a complete manual tailshaft from a HR31.
Other than that, I believe the tailshaft yoke is different between auto and manual. You could possibly get a new tailshaft made out of your old auto one, but I believe you will need the manual yoke to suit your manual box.
ECU/wiring - If you were keeping the standard engine, this would be easy, as you can keep the auto ECU and modify the wiring to negate the auto's neutral switch (basically connect two wires together). WHat engine are you going to?
Speedo sender - Yes you can use the same one from the auto in the R31. However it may get a bit inaccurate, if it wasn't already.
Cross member - Usually the easiest thing is to get the manual one if possible. Again this probably depends on what engine and box you are going to. Not sure if you can use the auto crossmember. When I have done auto to manual before I have always had a manual one.
HR31s don't have a clutch cable, it's a hydraulic clutch
So you will need:
- Clutch master cylinder (one from a local skyline will also work)
- Clutch lines (could probably also get these from a local skyline if neccessary)
- Clutch slave cylinder (can be bought new for ~$27 if u need, once again ask for local skyline part)
- clutch pushrod (if you get a secondhand clutch slave it should come with this. basically its just a metal bar)
Good luck man, it may seem like a big job, but it's worth it.