Bart, you can certainly order a shift knob from Nissan but they are not the same as the original, the new ones are fatter, more rounded. The original is quite slim. There was a thread about shift knobs going last winter and it covered everything.

Here it is,http://www.classiczcars.com/forums/help-me/47482-5-speed-knob-reproduction.html

Thanks. But the only information I found in that topic was that the original wooden shift knobs where slimmer, and the ones on Ebay ( like the link above ) are reproductions ?

Just came across a 5 speed ?

Datsun 5 Speed Wood Shift Knob 1200 240Z 510 240K B10 B110 120Y Bluebrid Nissan | eBay